Protective carbon layer for lithium (Li) metal anodes

ABSTRACT

This disclosure provides a battery including a cathode, an anode positioned opposite the cathode and a carbon interface layer. The carbon interface layer includes an electrically insulating flaky carbon layer conformally encapsulating the anode. A plurality of carbon nano-onions (CNOs) defining a plurality of interstitial pore volumes are interspersed throughout the electrically insulating flaky carbon layer. An electrolyte is in contact with the carbon interface layer and the cathode. A separator is positioned between the anode and the cathode. The electrically insulating flaky carbon layer can include graphene oxide (GO). The plurality of interstitial pore volumes can be configured to transport lithium (Li) ions between the anode and the cathode via the plurality of interstitial pore volumes in a bulk phase of the electrolyte. The carbon interface layer can be configured to inhibit growth of Li dendritic structures from the anode towards the cathode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation application and claimspriority to U.S. patent application Ser. No. 17/016,245, filed on Sep.9, 2020 and entitled “PROTECTIVE CARBON LAYER FOR LITHIUM (LI) METALANODES,” which is a continuation-in-part application claiming priorityto U.S. patent application Ser. No. 16/942,229, filed on Jul. 29, 2020and entitled “CARBON-BASED STRUCTURES FOR INCORPORATION INTO LITHIUM(LI) ION BATTERY ELECTRODES,” (now issued as U.S. Pat. No. 11,127,941),to U.S. patent application Ser. No. 16/942,266, filed on Jul. 29, 2020and entitled “ADVANCED LITHIUM (LI) ION AND LITHIUM SULFUR (LI S)BATTERIES,” (now issued as U.S. Pat. No. 11,133,495), and to U.S. patentapplication Ser. No. 16/942,305, filed on Jul. 29, 2020 and entitled“SYSTEMS AND METHODS OF MANUFACTURE OF CARBON-BASED STRUCTURESINCORPORATED INTO LITHIUM ION AND LITHIUM SULFUR (LI S) BATTERYELECTRODES,” (now issued as U.S. Pat. No. 11,127,942), to U.S. patentapplication Ser. No. 16/785,020, filed on Feb. 7, 2020 and entitled “3DSELF-ASSEMBLED MULTI-MODAL CARBON BASED PARTICLE” (now issued as U.S.Pat. No. 11,198,611) and to U.S. patent application Ser. No. 16/785,076,filed on Feb. 7, 2020 and entitled “3D SELF-ASSEMBLED MULTI-MODAL CARBONBASED PARTICLES INTEGRATED INTO A CONTINUOUS FILM LAYER,” (now issued asU.S. Pat. No. 11,299,397), both of which claim priority to U.S.Provisional Patent Application No. 62/942,103, filed on Nov. 30, 2019and entitled “3D HIERARCHICAL MESOPOROUS CARBON-BASED PARTICLESINTEGRATED INTO A CONTINUOUS ELECTRODE FILM LAYER,” and U.S. ProvisionalPatent Application No. 62/926,225, filed on Oct. 25, 2019 and entitled“3D HIERARCHICAL MESOPOROUS CARBON-BASED PARTICLES INTEGRATED INTO ACONTINUOUS ELECTRODE FILM LAYER,” all of which are assigned to theassignee hereof. The disclosures of all prior Applications areconsidered part of and are incorporated by reference in this PatentApplication.

TECHNICAL FIELD

This disclosure relates generally to suppressing lithium (Li) dendriticstructure formation on metallic lithium electrodes (anodes) and, morespecifically, to enabling stable and long-lifetime Li ion and lithiumsulfur (Li S) batteries.

DESCRIPTION OF RELATED ART

Lithium-ion (Li ion), lithium (Li) metal, and lithium sulfur (Li S)batteries are considered promising power sources for demandingapplications, such as electric vehicle (EV), hybrid electric vehicle(HEV), and modern portable electronic devices, such as laptop computersand smartphones. Compared to other alkali metals, Li metal offers thehighest specific capacity relative to any other metal ormetal-intercalated compound as an anode material. As a result, Li metalbatteries (such as those having solid Li metal foil anodes) have asignificantly higher energy density and power density than lithium-ionbatteries (traditionally featuring graphite anodes with ionic Liintercalated there-within). However, cycling stability and safetyconcerns, due to the highly reactive and explosive nature of elementalLi upon exposure to extreme forces experienced during, for example, avehicular collision, remain principal factors preventing wide-scalecommercialization of Li metal or Li S batteries featuring solid Li metalfoil anodes for EV, HEV, and microelectronic device applications. Andspecific cyclic stability and safety issues of Li metal and Li Srechargeable batteries are primarily related to the high tendency for Lito form dendritic structures that extend across the battery from theanode to the cathode during repeated charge-discharge cycles or anovercharge and contribute to internal electrical shorting and thermalrunaway.

Conventional efforts at addressing issues related to the growth ofdendritic structures during battery operation include implementation ofa multilayer separator that included a porous membrane and anelectro-active polymeric material contained within the separatormaterials. Aside from improvements to the separator, an intermediaryelectrode or layer positioned between the anode and the cathode has beenproposed and was separated from the cathode and anode by fiberglasspaper separators. This intermediary electrode includes carbon orgraphite material disposed on surfaces of a separator and serves as alow-capacity cathode that quickly discharges any Li dendrite that comesin contact with the getter layer. A surface layer (such as polynucleararomatic and polyethylene oxide) has also been proposed that enablestransfer of metal ions from the metal anode to the electrolyte and back.The surface layer is also electronically conductive so that the ionswill be uniformly attracted back onto the metal anode duringelectrodeposition. Internal shorting has also been shown to have beenprevented by using a multi-layered metal oxide film as a separator withsmall apertures through which Li ions can pass and the growth ofdendrites can be inhibited. A first thin film coating on the anode and asecond thin film coating on the cathode, with both coatings permeable tolithium ions, could also be effective in preventing dendrite formation.The first film can contain a large ring compound, an aromatichydrocarbon, a fluoro-polymer, a glassy metal oxide, a cross-linkedpolymer, or a conductive powder dispersion. Nevertheless,dendrite-preventing mechanisms of these films have yet to be clearlyexplained. And protective coatings for Li anodes, such as glassy surfacelayers of LiI—Li₃PO₄—P₂S₅, may be obtained from plasma assisteddeposition. Despite at least these and other earlier efforts, norechargeable Li metal batteries or Li S batteries equipped with a solidmetal Li anode have yet found reliable commercial success, thus creatinga need for a simpler, more cost-effective, and easier to implementapproach to preventing Li metal dendrite-induced internal short circuitand thermal runaway problems in Li metal batteries and otherrechargeable batteries.

SUMMARY

This Summary is provided to introduce in a simplified form a selectionof concepts that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tolimit the scope of the claimed subject matter.

One innovative aspect of the subject matter described in this disclosurecan be implemented as a battery including a cathode, an anode positionedopposite the cathode, and a carbon interface layer, which includes anelectrically insulating flaky carbon layer conformally encapsulating theanode and a plurality of carbon nano-onions (CNOs) defining a pluralityof voids interspersed throughout the electrically insulating flakycarbon layer. An electrolyte is in contact with the carbon interfacelayer and the cathode. A separator is positioned between the anode andthe cathode. The plurality of voids can be configured to transportlithium (Li) ions between the anode and the cathode via the plurality ofvoids in a bulk phase of the electrolyte. The carbon interface layer canhave a thickness approximately between 0.1 μm and 20 μm. The cathode caninclude a porous carbon-based structure configured to cyclically expandand contract a volume of the cathode during operational cycling of thebattery.

In some implementations, the carbon interface layer includes a filmhaving a Young's modulus greater than approximately 6 GPa and can beconfigured to inhibit growth of Li dendritic structures from the anodetowards the cathode. The separator can be configured to transport Liions between the anode and the cathode via the separator. Any one ormore CNOs of the plurality of CNOs can have a surface area ofapproximately 30 m²/g. The plurality of CNOs can be configured to adsorbpolysulfide (PS) onto exposed surfaces of each CNO. The plurality ofCNOs can be configured to inhibit PS anions from contacting the anode.

In some implementations, the anode can include a metal foil, which canhave a thickness approximately between 70 μm and 130 μm. The anode caninclude a carbon-based composite structure including any one or more ofa plurality of carbon nano-onions or a plurality of graphene plateletsfused together. The carbon-based composite structure is configured to beinfiltrated by a molten lithium (Li) metal, the molten Li metal caninclude one or more Li-containing droplets, domains, or single orpoly-crystalline domains. The metal foil can include a layer of Lihaving a thickness approximately between 25 μm and 50 μm. Theelectrically insulating flaky carbon layer can include interlayer pi-pibonds. A stack can include two or more electrically insulating flakycarbon films, wherein each electrically insulating flaky carbon layerfilm is substantially flat and configured to accommodate formation ofthe stack. The stack can be configured to inhibit crack growth. Thestack can include a plurality of gap regions, each gap region can bepositioned between adjacent electrically insulating flaky carbon filmswithin the stack and can be configured to receive a binder, which can beconfigured to bond two or more electrically insulating flaky carbonfilms together. The electrically insulating flaky carbon film can beconfigured to react with a Li metal provided by the anode and can beconfigured to produce lithium hydroxide (LiOH) upon reacting with the Limetal. The lithium hydroxide can be configured to produce asolid-electrolyte interphase (SEI) between the anode and theelectrolyte. The carbon interface layer can include one or more carbonderivatives, which can have a first pore concentration and a second poreconcentration different than the first pore concentration. The one ormore carbon derivatives can have a first surface area and a secondsurface area different than the first surface area. The carbonderivatives can be configured to react with a contaminant, which caninclude any one or more a polysulfide (PS), a binder, or an additive.The carbon interface layer can at least partially incorporate theadditive, which can be configured to conduct Li ions during operationalcycling of the battery. One or more carbon derivatives of the carboninterface layer is configured to chemically react with the contaminant.The carbon interface layer can be configured to adhere to Li provided bythe anode.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented as a method of fabricating a lithium (Li)anode. The method can include forming a slurry by mixing a plurality ofelectrically insulating flaky carbons and a plurality of carbonnano-onions (CNOs), casting the slurry onto a polyethylene terephthalate(PET) release film, drying the slurry, transferring the dried slurry onthe PET release film onto a lithium-clad copper foil of the Li anode byroll-laminating. Roll-laminating can include applying pressure to thedried slurry on the PET release film and forming a protectivecarbon-inclusive layer, calendaring the protective carbon-inclusivelayer onto the Li anode, and releasing the PET release film, wherein thecarbon-inclusive layer remains adhered to the Li anode upon release ofthe PET release film.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of the subject matter described in this disclosure are setforth in the accompanying drawings and the description below. Otherfeatures, aspects, and advantages of the subject matter will becomeapparent from the description, the drawings, and the claims.

FIG. 1A through 1E show diagrams of a carbon-based particle with variousdefined regions for electrical conduction and ion transport inaccordance with some aspects of the present disclosure.

FIG. 1F shows schematic diagrams representative of intermediate stepsfor the reduction of sulfur and/or the formation of polysulfides (PS),according to some implementations.

FIGS. 1G and 1H show schematics for placement and/or intercalation of Liions in carbon lattices and structures, according to someimplementations.

FIG. 2 show schematics for cavities that are formed extending depth-wiseinto several of the adjacent stacked FL graphene layers, according tosome implementations.

FIG. 3 shows a schematic of a multi-layered carbon-based scaffoldedstructure, according to some implementations.

FIG. 4A shows a schematic of the structure shown in FIG. 3 with lithium(Li) metal infused into nanoscale gaps therein, according to someimplementations.

FIG. 4B shows a schematic of a simplified version of the structure shownin FIG. 3 prepared as an anode with a hybrid artificialsolid-electrolyte interphase (A-SEI) layer encapsulating the anode,according to some implementations.

FIG. 4C shows the example shown in FIG. 4B prepared with an anode formedof the multi-layered carbon-based scaffolded structure shown in FIG. 3 ,according to some implementations.

FIG. 4D shows a table of various binders that can be used to enhance thehybrid A-SEI layer shown in FIG. 4B and FIG. 4C, according to someimplementations.

FIG. 4E shows an example of mechanical strength enhancing additive forthe A-SEI shown in FIG. 4B and FIG. 4C, according to someimplementations.

FIG. 4F shows an example formation pathway for a metal polyacrylateuseful to protect a Li electrode (such as an anode), according to someimplementations.

FIG. 4G shows a photograph of an example SnF₂/SBR coating on a controlHohsen Li/Cu foil, according to some implementations.

FIG. 4H shows a graph of the specific discharge capacity of an exampleLi—S full cell with a LiF/Li—Sn alloy hybrid A-SEI treated Li anode andan intact Hohsen Li control foil with a cathode, according to someimplementations.

FIG. 4I shows a photograph of an example Si₃N₄/SBR A-SEI coating on thecontrol Hohsen Li/Cu foil, according to some implementations.

FIG. 4J shows a graph of the specific discharge capacity of an exampleLi—S full cell prepared with a LiN3/Li—Si hybrid A-SEI treated Li anodeand an intact Hohsen Li control, according to some implementations.

FIG. 4K shows a photograph of an example graphite fluoride/SBR A-SEIcoating in a control Hohsen Li/Cu foil anode, according to someimplementations.

FIG. 4L shows a graph of the specific discharge capacity of an exampleLi—S full cell prepared with a LiF/graphite hybrid A-SEI treated Lianode and an intact Hohsen Li control with cathode, according to someimplementations.

FIG. 4M is an example schematic diagram of a carbon-containing layerincluding carbon allotropes with or without doping or functionalization,with particle sizes ranging from 0.01-10 μm, laminated on top of alithium-clad current collector foil as a functional anode for Li ion orLi S battery, according to some implementations.

FIG. 4N is an example schematic diagram of a roll-to-roll apparatusprepared for fabrication of a carbon-on-lithium anode that utilizes anymethod of compression to transfer a carbon containing coating onto thesurface of lithium from another substrate, such as roll-to-rolllamination and release, according to some implementations.

FIG. 4O is a photograph of an example protective carbon interface (PCI)suitable for implementation in or on an anode, such as that shown inFIG. 4M, according to some implementations.

FIG. 4P shows a graph of electrode specific capacity performance of anLi anode protected by the protective carbon interface (PCI) comparedagainst a reference pure Li metal electrode over cycle number, accordingto some implementations.

FIG. 4Q shows a graph of coulombic efficiency of an Li anode protectedby the protective carbon interface (PCI) compared against a referencepure Li metal electrode over cycle number, according to someimplementations.

FIG. 4R shows a graph of mean charge voltage of an Li anode protected bythe protective carbon interface (PCI) compared against a reference pureLi metal electrode over cycle number, according to some implementations.

FIG. 4S shows another graph of electrode specific capacity performanceof an Li anode protected by the protective carbon interface (PCI)compared against a nano-diamond layer, a reference pure Li metalelectrode, and a non-uniform interface layer over cycle number,according to some implementations.

FIG. 4T shows a photograph of a teardown of an example reference lithiumpouch cell showing a high degree of dendritic growth into the separator,which is represented by the transfer of the black mossy structure,according to some implementations.

FIG. 4U shows a photograph of a teardown of an example carbon-containinglayer protected Li anode, such as that shown in FIG. 4M, showing a lackof the mossy black protrusions found in the reference cell teardownshown in FIG. 4T and instead showing only a few spots of delaminatedLPCI that stuck to the separator upon deconstruction, according to someimplementations.

FIG. 4V shows a schematic diagram of a series of plasma spray torchespositioned in a continuous sequence above a roll-to-roll (R2R)processing apparatus, according to some implementations.

FIG. 5 shows a schematic diagram for an example Li ion or Li Selectrochemical cell, according to some implementations.

FIG. 6A shows a schematic diagram of the incorporation of metal powdersinto a carbon particle for Li wetting and infiltration, according tosome implementations.

FIGS. 6B and 6C show schematic diagrams for chemically non-reactivesystems and chemically reactive systems, respectively, according to someimplementations.

FIG. 7 shows an example process workflow where molten Li metal isinfiltrated into void spaces between carbon agglomerations, according tosome implementations.

FIG. 8A shows an equation for a rate of infiltration a carbon-basedstructure, according to some implementations.

FIGS. 8B and 8C show non-reactive and reactive systems regarding Liinfiltration into carbon structures, according to some implementations.

FIG. 9 shows a flowchart depicting example operations of lithiating andalloying a carbon-based structure, according to some implementations.

FIG. 10A shows a flowchart depicting example operations of preparing acarbon-based structure, according to some implementations.

FIG. 10B shows a flowchart depicting example operations of preparing Limaterials, according to some implementations.

FIG. 10C through FIG. 10P show flowchart depicting example operations offabricating an electrochemical cell electrode, according to someimplementations.

FIG. 11A through 11C show depicting example operations of preparing acarbon particle for lithiation, according to some implementations.

FIG. 12 shows a flowchart depicting example operations of performing Liinfusion of a carbon particle, according to some implementations.

FIG. 13 shows a schematic of an anode, according to someimplementations.

FIG. 14 shows a silicon and carbon anode performance over multiple usagecycles, according to some implementations.

FIGS. 15 and 16 show schematics s related to an idealized cathodeconfiguration with lithium sulfide (Li₂S) nanoparticles in graphenedispersed therein, according to some implementations.

FIGS. 17A and 17B show an enlarged portions of the carbon-basedparticles of FIGS. 1A through 1F, according to some implementations.

FIGS. 18A through 18E are micrographs of portions of a carbon particle,according to some implementations.

FIG. 19A shows a schematic of a 3D carbon-based cathode, according tosome implementations.

FIG. 19B shows a schematic diagram of a 3D carbon-based anode, accordingto some implementations.

FIG. 20A shows discharge and charge cycles of an example Li Selectrochemical cell, according to some implementations.

FIGS. 20B and 20C show battery performance charts for batteries equippedwith carbon-inclusive electrodes, according to some implementations.

FIG. 21 shows Raman spectra for 3D N-doped FL graphene, according tosome implementations.

FIG. 22 shows schematic diagrams of bilayer graphene, according to someimplementations.

FIG. 23 shows a method for preparing a 3D scaffolded film, according tosome implementations.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

Various aspects of the novel systems, apparatuses, and methods aredescribed more fully herein with reference to the accompanying drawings.The teachings disclosed can, however, be embodied in many differentforms and should not be construed as limited to any specific structureor function presented throughout this disclosure. Rather, these aspectsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the disclosure to those skilled in theart.

Based on the teachings herein one skilled in the art should appreciatethat the scope of the disclosure is intended to cover any aspect of thenovel systems, apparatuses, and methods disclosed herein, whetherimplemented independently of or combined with any other aspect of theinvention. For example, an apparatus can be implemented, or a method canbe practiced using any number of the aspects set forth herein. Inaddition, the scope of the invention is intended to cover such anapparatus or method which is practiced using other structure,functionality, or structure and functionality in addition to or otherthan the various aspects of the invention set forth herein. Any aspectdisclosed herein can be embodied by one or more elements of a claim.

Although some examples and aspects are described herein, many variationsand permutations of these examples fall within the scope of thedisclosure. Although some benefits and advantages of the preferredaspects are mentioned, the scope of the disclosure is not intended to belimited to benefits, uses, or objectives. Rather, aspects of thedisclosure are intended to be broadly applicable to a carbon-basedparticle self-nucleated in an atmospheric-pressure vapor flow stream ofa carbon-containing gas such as methane, the carbon-based particleincluding multiple electrically conductive three-dimensional (3D)aggregates of graphene sheets defining void spaces and ion conduitstherein, some of which are illustrated in the figures and in thefollowing description of the preferred aspects. The detailed descriptionand drawings are merely illustrative of the disclosure rather thanlimiting, the scope of the disclosure being defined by the appendedclaims and equivalents thereof.

Definitions

Li-Ion Batteries

A Li-ion battery is a type of secondary, alternatively referred to as arechargeable, battery. Such battery technology has shown great promisein recent years as power sources that can lead to an electric vehicle(EV) revolution by facilitating the widespread implementation of EVsacross numerous applications. Accordingly, the development of newmaterials for various components of Li-ion batteries is the focus ofresearch in the field of materials science. Li-ion batteries power mostmodern portable devices and seem to have overcome psychological barriersof the consuming public against the use of such high energy densitydevices on a larger scale for more demanding applications, such as EVs.

Regarding operation, in Li-ion batteries, Li ions (Lit) migrate from thenegative electrode, also referred to as the anode, through anelectrolyte, which can be in any one or more of a liquid phase or a gelphase, to the positive electrode during discharge cycles and returnduring charging cycles. Conventional Li-ion batteries can use anintercalated Li compound as a formative material at the positiveelectrode and graphite at the negative electrode. Such batteries can becharacterized by their relatively high energy density measured as aspecific capacity having the units of milliamp hours per gram (mAh/g),no “memory-effect”—describing the situation in which nickel-cadmiumbatteries gradually lose their maximum energy capacity if they arerepeatedly recharged after being only partially discharged—and lowself-discharge. Unfortunately, unlike many non-Li conventional batterychemistries, Li ion batteries can, due to the highly reactive nature ofelemental and ionic Li, present a safety hazard. Li batteries candeteriorate unexpectedly, including through explosions and fires, uponpuncture, abrasive contact, or even excessively charged. In spite ofsuch drawbacks, the high energy density of Li ion batteries remainsattractive as it permits for longer usable lifespans of several hoursbetween charging cycles as well as longer cycle life, referring to theelectric current delivery or output performance of a given Li-ionbattery over multiple repeat charge-discharge, such as partial or totalcharge depletion, cycles.

Overall, Li metal, due to its high theoretical specific capacity of3,860 mAh/g, low density (0.59 g cm-3) and low negative electrochemicalpotential, such as −3.040 V compared to a standard hydrogen electrode,still appears as an ideal material for the negative electrode ofsecondary Li-ion batteries. But problems continue to persist, such asdendrite growth, referring the growth of a branching tree-like structurewithin the battery itself, which can be caused by Li precipitates.Dendrites, upon growing from one electrode to contact the other, cancause serious safety concerns related to short-circuits, and limitedCoulombic efficiency, discussing to the charge efficiency by whichelectrons are transferred in batteries during deposition and strippingoperations inherent in Li-ion batteries. Such challenges have previouslyimpeded Li ion battery applications.

Concerns related to safety of earlier-developed Li secondary batterieshave led to the development and refinement of current generation Li-ionsecondary batteries. Such Li-ion batteries typically featurecarbonaceous materials used as an anode, such carbonaceous anodematerials including:

graphite;

amorphous carbon; and,

graphitized carbon.

The first type of the three carbonaceous materials presented aboveincludes naturally occurring graphite and synthetic graphite orartificial graphite, such as Highly Oriented Pyrolytic Graphite, HOPG.Form of graphite can be intercalated with Li, such as that obtained froma molten Li metal source. The resulting Graphite Intercalation Compound(GIC) may be expressed as Li_(x)C₆, where X is typically less than 1. Tolimit or otherwise minimize loss in energy density due to thereplacement of Li metal with the GIC, X in Li_(x)C₆ must be maximizedand the irreversible capacity loss (Q_(ir)), in the first charge of thebattery must be minimized.

As a result, the maximum amount of Li that can be reversiblyintercalated into the interstices between graphene planes of a perfectgraphite crystal is generally believed to occur in a graphiteintercalation compound represented by Li_(x)C₆ (x=1), corresponding to atheoretical 372 mAh/g. However, such a limited specific capacity cannotadequately satisfy the demanding requirements of higher energy-densitypower needs of modern electronics and EVs. Accordingly, carbon-basedanodes, such as graphite intercalated with Li, can demonstrate extendedcycle lifespans due to the presence of a surface-electrolyte interfacelayer (SEI), which results from the reaction between Li and surroundingelectrolyte, or between Li and the anode surface/edge atoms orfunctional groups, during the initial several charge-discharge cycles.Li ions consumed in this reaction, referring to the formation of theSEI, may be derived from some of the Li ions originally intended forcharge transfer, referring to a process of the dissociation of elementalLi when intercalated with carbon in a carbon-based structure, such aswithin the anode.

Charge transfer can occur during Li ion movement in electrolyte across aporous separator to the cathode as related to electron release andtransport to facilitate electric current conduction to power a loadduring typical Li ion battery discharge cycles. During repeated Li ionbattery charge-discharge cycles, the SEI is formed and some of the Liions migrating through the electrolyte become part of the inert SEIlayer and are described as becoming “irreversible”, in that they can nolonger be an active element or ion used for charge transfer. As aresult, it is desirable to minimize the amount of Li used for theformation of an effective SEI layer. In addition to SEI formation,Q_(ir), has been attributed to graphite exfoliation caused byelectrolyte/solvent co-intercalation and other side reactions.

Next, amorphous carbon contains no, or very little, micro- ornano-crystallites and can include both “soft carbon” and “hard carbon”.Soft carbon refers to a carbon material that can be graphitized at atemperature of about 2,500° C. or higher. In contrast, hard carbonrefers to a carbon material that cannot be graphitized at a temperaturehigher than 2,500° C.

In practice and industry, the so-called “amorphous carbons” commonlyused as anode active materials may not be purely amorphous, but rathercontain some minute amount of micro- or nano-crystallites, eachcrystallite being defined as a small number of graphene sheets orientedas basal planes that are stacked and bonded together by weak van derWaals forces. The number of graphene sheets can vary between one andseveral hundreds, giving rise to a c-directional dimension, such asthickness L_(e), of typically 0.34 nm to 100 nm. The length or width(L_(a)) of these crystallites is typically between tens of nanometers tomicrons. Among this class of carbon materials, soft and hard carbons canbe produced by low-temperature pyrolysis (550-1,000° C.) and exhibit areversible specific capacity of 400-800 mAh/g in the 0-2.5 V range. Aso-called “house-of-cards” carbonaceous material has been produced withenhanced specific capacities approaching 700 mAh/g.

Research groups have obtained enhanced specific capacities of up to 700mAh/g by milling graphite, coke, or carbon fibers and have explained theorigin of the additional specific capacity with the assumption that indisordered carbon containing some dispersed graphene sheets, referred toas “house-of-cards” materials, Li ions are adsorbed on two sides of asingle graphene sheet. It has been also proposed that Li readily bondsto a proton-passivated carbon, resulting in a series of edge-oriented Lito C—H bonds. This can provide an additional source of Li⁺ in somedisordered carbons. Other research suggested the formation of Li metalmonolayers on the outer graphene sheets of graphite nano-crystallites.The discussed amorphous carbons were prepared by pyrolyzing epoxy resinsand may be referred to as polymeric carbons. Polymeric carbon-basedanode materials have also been studied.

Chemistry, performance, cost, and safety characteristics may vary acrossLi ion battery variants. Handheld electronics may use Li polymerbatteries using a polymer gel as electrolyte with Li cobalt oxide(LiCoO₂) as cathode material. Such a configuration can offer relativelyhigh energy density but may present safety risks, especially whendamaged. Li iron phosphate (LiFePO₄), Li ion manganese oxide battery(LiMn₂O₄, Li₂MnO₃, or LMO), and Li nickel manganese cobalt oxide(LiNiMnCoO₂ or NMC) all offer lower energy density yet provide longeruseful lives and less likelihood of fire or explosion. Thus, suchbatteries are widely used for electric tools, medical equipment, andother roles. NMC in particular is often considered for automotiveapplications.

Lithium (Li)-Sulfur (S) Batteries

The lithium-sulfur battery, referred to herein as a Li—S battery, is atype of rechargeable battery, notable for its high specific energy. Therelatively low atomic weight of Li and moderate atomic weight of Sresults in Li—S batteries being relatively light, at about the densityof water).

Li—S batteries may succeed lithium-ion cells because of their higherenergy density and reduced cost due to the use of sulfur. Li—S batteriescan offer specific energies at approximately 500 Wh/kg, which issignificantly better than many conventional Li-ion batteries, which aretypically in the range of 150-250 Wh/kg. Li—S batteries with up to 1,500charge and discharge cycles have been demonstrated. Although presentingmany advantages, a key faced by the Li—S battery is the polysulfide“shuttle” effect that results in progressive leakage of active materialfrom the cathode resulting in an overall low life cycle of the battery.And, the extremely low electrical conductivity of a sulfur cathoderequires an extra mass for a conducting agent to exploit the wholecontribution of active mass to the capacity. Large volumetric expansionof S cathode from elemental S to Li₂S and a large amount of electrolyteneeded are also problem areas demanding attention.

Chemical processes in the Li—S cell include Li dissolution from theanode surface and incorporation into alkali metal polysulfide saltsduring discharge, and reverse lithium plating to the anode whilecharging. At the anodic surface, dissolution of the metallic lithiumoccurs, with the production of electrons and lithium ions during thedischarge and electrodeposition during the charge. The half-reaction isexpressed as:Li⇄Li⁺ +e ⁻  (Eq. 1)

Similar to that observed in Li ion batteries, dissolution and/orelectrodeposition reactions can cause, over time, problems of unstablegrowth of the solid-electrolyte interface (SEI), generating active sitesfor the nucleation and dendritic growth of Li. Dendritic growth isresponsible for the internal short circuit in Li batteries and leads tothe death of the battery itself.

In Li—S batteries, energy is stored in the sulfur electrode (S₈), whichis the cathode. During cell discharge cycles, Li ions in the electrolytemigrate from the anode to the cathode where the S is reduced to lithiumsulphide (Li₂S). The sulfur is reoxidized to S₈ during the refillingphase. The semi-reaction is expressed at a high level of abstraction,for explanatory purposes, as:S+2Li⁺+2e ⁻

Li₂S(E°≈2.15V vs Li/Li⁺)  (Eq. 2)

In reality, the S reduction reaction to Li₂S is significantly morecomplex and involves the formation of several Li polysulphides(Li₂S_(x), 8<x<1) at decreasing chain length according to the order:Li₂S₈→Li₂S₆→Li₂S₄→Li₂S₂→Li₂S  (Eq. 3)

The final product is a mixture of Li₂S₂ and Li₂S rather than just pureLi₂S, due to the slow reduction kinetics at Li₂S. This is in contrastwith conventional Li ion cells, where the Li ions are intercalated inboth of the anode and the cathode. For example, in Li S battery systems,each S atom can host two Li ions. Typically, Li ion batteries canaccommodate only 0.5-0.7 lithium ions per host atom. As a result, Li—Sallows for a much higher Li storage density. Polysulfides (PS) arereduced on the cathode surface in sequence while the cell isdischarging:S₈→Li₂S₈→Li₂S₆→Li₂S₄→Li₂S₃  (Eq. 4)

Across a porous diffusion separator, S polymers form at the cathode asthe cell charges:Li₂S→Li₂S₂→Li₂S₃→Li₂S₄→Li₂S₆→Li₂S₈→S₈  (Eq. 5)These reactions can be analogous to those in the sodium (Na)—S battery.

Primary challenges concerning Li—S battery systems include the lowrelatively low conductivity of S, its massive volume change upondischarging, and finding a suitable cathode, such as that constructedfrom any of the presently disclosed carbon-based structures, is thefirst step for commercialization of Li—S batteries. Currently,conventional Li S batteries use a carbon/sulfur cathode and a Li anode.Sulfur is naturally abundant and relatively low cost, but haspractically no electroconductivity, 5×10⁻³⁰ S·cm-1 at 25° C. A carboncoating provides the missing electroconductivity. Carbon nanofibersprovide an effective electron conduction path and structural integrity,at the disadvantage of higher cost.

One problem with the Li—S design is that when the S in the cathodeabsorbs Li, volume expansion of the Li_(x)S compositions takes place,and predicted volume expansion of Li₂S is nearly 80% of the volume ofthe original S. This causes large mechanical stresses on the cathode,which is a major cause of rapid degradation. Such process reduces thecontact between the carbon (C), the S and prevents the flow of Li ionsto the carbon surface.

Mechanical properties of the lithiated S compounds are stronglycontingent on the Li content, and with increasing Li content, thestrength of lithiated S compounds improves, although this increment isnot linear with Li. One of the primary shortfalls of most Li—S cellsconcerns unwanted reactions with the electrolyte. While S and Li₂S arerelatively insoluble in most electrolytes, many intermediatepolysulfides (PS) are not such that dissolving Li₂S_(n) into theelectrolyte can cause irreversible loss of active S. Use of highlyreactive Li as a negative electrode causes dissociation of most of thecommonly used other type electrolytes. Use of a protective layer in theanode surface has been studied to improve cell safety, such as usingTeflon coating showed improvement in the electrolyte stability, UPON,Li₃N also exhibited promising performance.

The “shuttle” effect has been observed to be the primary cause ofdegradation in a Li—S battery. The Li PS Li₂S_(x) (6≤x≤8) is highlysoluble in the common electrolytes used for Li—S batteries. They areformed and leaked from the cathode, and they diffuse to the anode, wherethey are reduced to short-chain PS and diffuse back to the cathode wherelong-chain PS is formed again. This process results in the continuousleakage of active material from the cathode, lithium corrosion, lowcoulombic efficiency, and low battery life due to batteryself-discharge. Moreover, the “shuttle” effect is responsible for thecharacteristic self-discharge of Li—S batteries, because of slowdissolution of PS, which occurs also in rest state. The “shuttle” effectin Li—S battery can be quantified by a factor f_(c) (0<f_(c)<1),evaluated by the extension of the charge voltage plateau. The factor fcis given by the expression:

$\begin{matrix}{{fc} = \frac{k_{s}{q_{up}\left\lbrack S_{tot} \right\rbrack}}{I_{c}}} & \left( {{Eq}.6} \right)\end{matrix}$where k_(s), q_(up), [S_(tot)] and I_(c) are respectively the kineticconstant, specific capacity contributing to the anodic plateau, thetotal sulfur concentration and charge current.Electrical Conductance of Carbon-based Materials

Advances in high conductance carbon materials such as carbon nanotubes(CNT), graphene, amorphous carbon, and/or crystalline graphite inelectronics allows for the printing of these materials onto many typesof surfaces without requiring usage of printed circuit boards, andwithout the use of materials or compounds that have been identified asbeing toxic to humans. Usage of high conductance carbon as a feedstockmaterial or other material during any one or more of the additivemanufacturing processes described above may facilitate the fabricationof batteries with micro-lattice structures suitable for enhancedfunctionality, electric power storage and delivery, and optimalefficiency. Although many of the devices described may serve as powersources such as batteries or capacitors, those of skill in the art willappreciate that printing technologies, such as 3D printing, may beconfigured using high conductance carbon materials such as carbonnanotubes (CNT), graphene, amorphous carbon, or crystalline graphite toform other electronic devices.

Printing technologies using high conductance carbon materials such ascarbon nanotubes (CNT), graphene, amorphous carbon, or crystallinegraphite may be implemented and/or otherwise incorporated in thefabrication of the following devices: antennas, tuned antennas, sensors,biosensors, energy harvesters, photocells, and other electronic devices.

Graphene

Graphene is an allotrope of carbon in the form of a single layer ofatoms in a two-dimensional hexagonal lattice in which one atom formseach vertex. It is the basic structural element of other allotropes,including graphite, charcoal, carbon nanotubes and fullerenes. It canalso be considered as an indefinitely large aromatic molecule, theultimate case of the family of flat polycyclic aromatic hydrocarbons.

Graphene has a special set of properties which set it apart from otherelements. In proportion to its thickness, it is about 100 times strongerthan the strongest steel. Yet its density is dramatically lower than anyother steel, with a surfacic, such as surface-related, mass of 0.763 mgper square meter. It conducts heat and electricity very efficiently andis nearly transparent. Graphene also shows a large and nonlineardiamagnetism, even greater than graphite and can be levitated by Nd—Fe—Bmagnets. Researchers have identified the bipolar transistor effect,ballistic transport of charges and large quantum oscillations in thematerial. Its end-use application areas are widespread, finding uniqueimplementations in advanced materials and composites, as well as beingused as a formative material to construct ornate scaffolds usable in Liion battery electrodes to enhance ion transport and electric currentconduction to yield specific capacity and power delivery figures nototherwise attainable by conventional battery technologies.

Chemical Functionalization of Graphene

Functionalization implies the process of adding new functions, features,capabilities, or properties to a material or substance by altering thesurface chemistry of the material. Functionalization is used throughoutchemistry, materials science, biological engineering, textileengineering, and nanotechnology and may be performed by attachingmolecules or nanoparticles to the surface of a material, with a chemicalbond or through adsorption, the adhesion of atoms, ions or moleculesfrom a gas, liquid or dissolved solid to a surface to create a film ofthe adsorbate on the surface of the adsorbent without forming a covalentor ionic bond thereto.

Functionalization and dispersion of graphene sheets may be of criticalimportance to their respective end-use applications. Chemicalfunctionalization of graphene enables the material to be processed bysolvent-assisted techniques, such as layer-by-layer assembly,spin-coating, and filtration and also prevents the agglomeration ofsingle layer graphene (SLG) during reduction and maintains the inherentproperties of graphene.

Currently, the functionalization of graphene may be performed bycovalent and noncovalent modification techniques. In both instances,surface modification of graphene oxide followed by reduction has beencarried out to obtain functionalized graphene. It has been found thatboth the covalent and noncovalent modification techniques are veryeffective in the preparation of processable graphene.

However, electrical conductivity of functionalized graphene has beenobserved to decrease significantly compared to pure graphene. Moreover,the surface area of the functionalized graphene prepared by covalent andnon-covalent techniques decreases significantly due to the destructivechemical oxidation of flake graphite followed by sonication,functionalization, and chemical reduction. To overcome these problems,studies have been reported on the preparation of functionalized graphenedirectly from graphite in a one-step process. In all these cases,surface modification of graphene can prevent agglomeration andfacilitates the formation of stable dispersions. Surface modifiedgraphene can be used for the fabrication of polymer nanocomposites, Liion battery electrodes, super-capacitor devices, drug delivery system,solar cells, memory devices, transistor device, biosensor, etc.

Graphite

Graphite, as commonly understood and as referred to herein, implies acrystalline form of elemental carbon with atoms arranged in a hexagonalstructure. Graphite occurs naturally in this form and is the most stableform of carbon under standard, such as atmospheric, conditions.Otherwise, under high pressures and temperatures, graphite converts todiamond. Graphite is used in pencils and lubricants. Its highconductivity makes it useful in electronic products such as electrodes,batteries, and solar panels.

Roll-to-Roll (R2R) Processing

R2R processing refers to the process of creating electronic devices on aroll of flexible plastic or metal foil. R2R processing may also refer toany process of applying coatings, printing, or performing otherprocesses starting with a roll of a flexible material and re-reelingafter the process to create an output roll. These processes, and otherssuch as sheeting, may be grouped together under the general term“converting”. When the rolls of material have been coated, laminated, orprinted they can be subsequently cut and/or slit to their finished sizeon a slitter rewinder.

R2R processing of large-area electronic devices may reduce manufacturingcost. Other applications could arise which take advantage of theflexible nature of the substrates, such as electronics embedded intoclothing, 3D-printed Li ion batteries, large-area flexible displays, androll-up portable displays.

Oxidation-Reduction (Redox) Reactions

Redox are a type of chemical reaction in which the oxidation states ofatoms are changed. Redox reactions are characterized by the transfer ofelectrons between chemical species, most often with one species, thereducing agent, undergoing oxidation by losing electrons while anotherspecies, such as the oxidizing agent, undergoes reduction by gainselectrons. The chemical species from which the electron is stripped issaid to have been oxidized, while the chemical species to which theelectron is added is said to have been reduced.

Intercalation

Intercalation is the reversible inclusion or insertion of a molecule, orion, into materials with layered structures. Examples are found ingraphite, graphene, and transition metal dichalcogenides.

Li Intercalation into Bi- or Multi-Layer Graphene

Electrical storage capacity of graphene and the Li-storage process ingraphite currently present challenges requiring further development inthe field of Li ion batteries. Efforts have therefore been undertaken tofurther develop three-dimensional bi-layer graphene foam with fewdefects and a predominant Bernal stacking configuration, a type ofbilayer graphene where half of the atoms lie directly over the center ofa hexagon in the lower graphene sheet, and half of the atoms lie over anatom, and to investigate its Li-storage capacity, process, kinetics, andresistances. Li atoms may be stored only in the graphene interlayer.Further, various physiochemical characterizations of the staged Libilayer graphene products further reveal the regular Li-intercalationphenomena and illustrate this Li storage pattern of two-dimensions.

Electrochemical Capacitors (ECs)

Electrochemical capacitors (ECs), also referred to as ultracapacitors orsupercapacitors, are being considered for uses in hybrid or full EVs.ECs can supplement, or in certain uses replace, traditional batteries,including high-performance Li ion batteries, used in an EVs to provideshort bursts of power, such as that needed for forward propulsion, oftenneeded for rapid acceleration. Traditional batteries may still be usedprovide uniform power for cruising at normal highway speeds, butsupercapacitors, with their ability to release energy much more quicklythan batteries, may activate and supplement battery-provided power atspecific times, such as when a so-equipped car needs to accelerate, suchas for merging, passing, emergency maneuvers, and hill climbing.

ECs must also store sufficient energy to provide an acceptable drivingrange, such as from 220-325 miles or more. And, to be cost- andweight-effective relative to additional battery capacity, ECs mustcombine adequate specific energy and specific power with long cycle lifeand meet cost targets as well. Specifically, ECs for application in EVsmust store about 400 Wh of energy, be able to deliver about 40 kW ofpower for about 10 seconds and provide high cycle-life, such as >100,000cycles.

The high volumetric capacitance density of an EC, such as 10 to 100times greater than conventional capacitors, derives from using porouselectrodes, which may incorporate, feature, and/or be constructed fromscaffolded graphene-based materials, to create a large effective “platearea” and from storing energy in the diffuse double layer. This doublelayer, created naturally at a solid-electrolyte interface when voltageis imposed, has a thickness of only about 1-2 nm, therefore forming anextremely small effective “plate separation.” In some ECs, stored energyis further augmented by pseudo-capacitance effects, occurring again atthe solid-electrolyte interface due to electrochemical phenomena such asthe redox charge transfer. The double layer capacitor is based on a highsurface area electrode material, such as activated carbon, immersed inan electrolyte. A polarized double layer is formed atelectrode-electrolyte interfaces providing high capacitance.

Overview

Introduction

Technological advances concerning modern carbon-based materials such asgraphene have, in turn, enhanced applications of such materials in manyend-use areas, such as in advanced secondary batteries. Such batteriescan employ electrochemical Li intercalation or de-intercalation to takeadvantage of favorable properties of carbon and carbon-based materials,which can depend significantly on their respective morphology,crystallinity, orientation of crystallites, and defects as well. Forinstance, the electric storage capacity of a Li-ion battery can beenhanced by the selection and integration of desirable nano-structuredcarbon materials such as carbon in certain allotropes such as graphiteand graphene, or nano-sized graphite, nanofibers, isolated single walledcarbon nanotubes, nano-balls, and nano-sized amorphous carbon, eachhaving small carbon nanostructures in which no dimension is greater thanabout 2 μm.

Known methods for fabricating carbon and Li-ion electrodes forrechargeable Li cells include steps for forming a carbon electrode. Sucha carbon electrode can be composed of graphitic carbon particles adheredto each other by an ethylene propylene diene monomer binder used toachieve a carbon electrode capable of subsequent intercalation byLi-ions. The carbon electrode is then reacted with infiltrated lithium(Li) metal to incorporate Li-ions obtained therefrom into graphiticcarbon particles of the electrode. A voltage can be repeatedly appliedto the carbon electrode to initially cause a surface reaction betweenthe Li-ions and to the carbon and subsequently cause intercalation ofthe Li-ions into crystalline layers of the graphitic carbon particles.With repeated application of the voltage, intercalation can be achievedto near a theoretical maximum and assist in the conduction of electricalcurrent as may be desirable.

Other exfoliated graphite-based hybrid material compositions relate to:

-   -   micron- or nanometer-scaled particles or coating which are        capable of absorbing and desorbing alkali or alkaline metal        ions, particularly, Li ions; and,    -   exfoliated graphite flakes that are substantially interconnected        to form a porous, conductive graphite network including pores        defined therein.        The particles or coating resides in a pore of the network or is        attached to a flake of the network. The exfoliated graphite        amount is in the range of 5% to 90% by weight and the number of        particles or amount of coating is in the range of 95% to 10% by        weight.

Also, high-capacity silicon-based anode active materials have been shownto be effective in combination with high-capacity Li rich cathode activematerials. Supplemental Li is shown to improve the cycling performanceand reduce irreversible capacity loss for some silicon based activematerials. Silicon based active materials can be formed in compositeswith electrically conductive coatings, such as pyrolytic carbon coatingsor metal coatings, and composites can also be formed with otherelectrically conductive carbon components, such as carbon nano fibersand carbon nanoparticles.

And, known rechargeable batteries of an alkali metal having an organicelectrolyte experiences little capacity loss upon intercalation of thecarbonaceous electrode with the alkali metal. The carbonaceous electrodemay include a multi-phase composition including both highly graphitizedand less graphitized phases or may include a single phase, highlygraphitized composition subjected to intercalation of Li at above about50° C. Incorporation of an electrically conductive filamentary materialsuch as carbon black intimately interspersed with the carbonaceouscomposition minimizes capacity loss upon repeated cycling.

Otherwise, a known Li based anode material can be characterized byincluding 1 m²/g or more of carbonaceous anode active material specificsurface area, a styrene-butadiene rubber binder, and a fiber diameterformed to 1,000 nanometers of carbon fiber. Such anode materials areused for Li batteries, which have desirable characteristics, such as alow electrode resistance, high strength of the electrode, anelectrolytic solution having excellent permeability, high energy densityand a high-rate charge/discharge. The negative electrode materialcontains 0.05 to 20 mass % of carbon fibers and a styrene at 0.1 to 6.0%by mass. Butadiene rubber forms the binder and may further contain 0.3to 3% by mass thickener, such as carboxymethyl methylcellulose.

Existing technologies have been shown that relate to a battery that hasan anode active material that has been:

-   -   pre-lithiated; and,    -   pre-pulverized.        Such an anode may be prepared with a method that comprises:    -   providing an anode active material;    -   intercalating or absorbing a desired amount of Li into the anode        active material to produce a pre-lithiated anode active        material;    -   comminuting, referring to the reduction of solid materials from        one average particle size to a smaller average particle size, by        crushing, grinding, cutting, vibrating, or other processes, the        pre-lithiated anode active material into fine particles with an        average size less than 10 μm, preferably <1 μm and most        preferably <200 nm; and,    -   combining multiple fine particles of the pre-lithiated anode        active material with a conductive additive and/or a binder        material to form the anode. The pre-lithiated particles are        protected by a Li ion-conducting matrix or coating material. The        matrix material is reinforced with nano graphene platelets.

Graphitic nanofibers have also been disclosed and include tubularfullerenes, commonly called “buckytubes”, nano tubes and fibrils, whichare functionalized by chemical substitution, are used as electrodes inelectrochemical capacitors. The graphitic nanofiber-based electrodeincreases the performance of the electrochemical capacitors. Preferrednanofibers have a surface area greater than about 200 m²/gm and aresubstantially free of micropores.

And, known high surface area carbon nanofibers have an outer surface onwhich a porous high surface area layer is formed. Methods of making thehigh surface area carbon nanofiber include pyrolizing a polymericcoating substance provided on the outer surface of the carbon nanofiberat a temperature below the temperature at which the polymeric coatingsubstance melts. The polymeric coating substance used as the highsurface area around the carbon nanofiber may include phenolics such asformaldehyde, polyacrylonitrile, styrene, divinyl benzene, cellulosicpolymers and cyclotrimerized diethynyl benzene. The high surface areapolymer which covers the carbon nanofiber may be functionalized with oneor more functional groups.

Synthesis of the Presently Disclosed Carbons

As presented above, conventional Li-intercalated carbon-basedcompositions or compounds may include traditional battery electrodematerials such as:

-   -   graphene or multi-layer 3D graphene particles;    -   electrically conductive carbon particles; and,    -   binder, such as that provided as a fluid, such as a liquid, form        and/or in particulate form, configured to retain carbon-based        particle in their respective desired positions and to provide        overall structural integrity to carbon-based systems.

In conventional techniques, particles are all typically deposited, suchas being dropped into, existing slurry cast electrodes including currentcollectors made from metal foil such as copper. Slurry typically isprepared to contain an organic binder or binder material referred to asNMP, an organic compound consisting of a 5-membered lactam, used in thepetrochemical and plastics industries as a solvent, exploiting itsnonvolatility and ability to dissolve diverse materials. The ratio ofactive materials to conductive carbon or carbon-based particles isusually at 5 parts of conductive carbon to a predominant balance ofactive material with a nominal quantity of binder or binding material,such as NMP, included as well. The relative amounts of binder andconductive phases of carbon may be dictated by creating an electricallyconductive path or paths between larger particles of those mentioned.

Regarding difficulties related to binder implementation and usage insecondary batteries, studies have shown that developing high-performancebattery systems requires the optimization of every battery component,from electrodes and electrolyte to binder systems. However, theconventional strategy to fabricate battery electrodes by casting amixture of active materials, a nonconductive polymer binder, and aconductive additive onto a metal foil current collector usually leads toelectronic or ionic bottlenecks and poor contacts due to the randomlydistributed conductive phases, which can be an issue that can beobserved in either the anode or the cathode. And, when high-capacityelectrode materials are employed, the high stress generated duringelectrochemical reactions can disrupt the mechanical integrity oftraditional binder systems, resulting in decreased cycle life ofbatteries. Thus, there is a critical need to design novel and robustbinder systems, or scaffolded carbon-based electrode structures thatdemonstrate structural integrity absent of usage of a binder, that canprovide reliable, low-resistance, and continuous internal voids,micropores, and pathways to retain active material when and wheredesirable during battery charge-discharge cycles, and to connect allregions of the electrode.

In contrast to that traditionally done, and to address shortcomings ofbinder performance related to decreased cycle life of batteries, thepresently disclosed inventive compositions of matter and methods orprocesses for the production thereof can eliminate:

-   -   any and all forms of a binder phase; and,    -   potentially certain regions, features and/or aspects of a        conductive phase defined by larger carbon-based particles, such        as those including graphite, and/or forms of graphene extracted        or otherwise created from the exfoliation of graphite.

This is done by fabricating a particle where interconnected 3Dagglomerations of multiple layers of graphene sheets fuse or sintertogether, such as randomly, or with controlled directionality such asorthogonally, or otherwise adjoin together to serve as a type ofintrinsic, self-supporting, “binder” or joining material that serves asa binder replacement, effectively allowing for the elimination of aseparate traditional binder material to achieve substantial weightreduction. Such a format also permits for the elimination of a separateand dedicated current collector, which is typically a required componentof many batteries. Elimination of the binder phase and/or the currentcollector, provide for beneficial and desirable features, such as:

-   -   having low per-unit production cost allowing for        mass-producibility,    -   high reversible specific capacity,    -   low irreversible capacity,    -   small particle sizes, such as permitting for high        throughput/rate capacity,    -   compatibility with commonly used electrolytes for convenient        integration and usage in commercial battery applications, and    -   long charge-discharge cycle life for consumer benefit, across        any number of demanding end-use applications, including        automobiles, airplanes, and spacecraft.

Notably, techniques disclosed herein yield unexpected favorable results.They do not require traditional processes to create graphene sheets suchas from the exfoliation of graphite, and instead synthesize one or morea multi-modal carbon-based s from an atmospheric plasma-based vapor flowstream. Synthesis of carbon-based particles can occur either in-flightto nucleate from an initially formed carbon-based homogenous nucleationor during deposition directly onto a supporting or sacrificialsubstrate. Therefore, any one or more of the presently disclosedtechniques permit for the growth of ornate carbon-based structuresindependent of a traditionally required seed particle upon whichnucleation occurs.

In conventional techniques, the production of functional graphene reliesupon usage of graphite as a starting material. Graphite, being aconductive material, has been used as an electrode in batteries andother electrochemical devices. In addition to its function as an inertelectrode, electrochemical methods have been employed to form graphiteintercalation compounds (GICs) and, more recently, to exfoliate graphiteinto few-layered graphene. Exfoliation, as generally understood and asreferred to herein, implies—in an intercalation chemistry relatedcontext—the complete separation of layers of material, and typicallyrequires aggressive conditions involving highly polar solvents andaggressive reagents. Electrochemical methods are attractive as theyeliminate the use of chemical oxidants as the driving force forintercalation or exfoliation, and an electromotive force is controllablefor tunable GICs. More importantly, the extensive capabilities ofelectrochemical functionalization and modification enable the facilesynthesis of functional graphene and its value-added nanohybrids.

Unlike exfoliation, inclusive of the thermal exfoliation of graphite toproduce graphene, the presently disclosed methods relate to one or morecarbon-inclusive gaseous species, such as those including methane (CH₄),being flowed into a reaction chamber of a microwave-based or thermalreactor. Upon receipt of energy, such as that provided byelectromagnetic radiation and/or thermal energy, incoming gaseousspecies spontaneously crack to form allotropes with other crackedcarbons from additional gaseous species supplied into the reactor tocreate an initial carbon-based site such as a formed particle, whicheither has or otherwise facilitates:

-   -   additional particles that grow or nucleate off of defects from        that initial formed particle; or,    -   orthogonally fuse or sinter additional carbon-based particles,        where there is sufficient local energy at the collision spot for        the colliding particles to combine.        System Structure        Carbon-Based Particles—In Detail

FIG. 1A shows a carbon-based particle 100A having controllableelectrical and ionic conducting gradients therein, within which variousaspects of the subject matter disclosed herein may be implemented. Thecarbon-based particle 100A can be synthesized through self-assemblyindependent of a binder to feature multi-modal dimensions, includingvarious orifices, conduits, voids, pathways, conduits or the like, anyone or more defined to have a specific dimension, such as beingmesoporous. A mesoporous material implies a material containing poreswith diameters between 2 and 50 nm, according to IUPAC nomenclature. Forthe purposes of comparison, IUPAC defines microporous material as amaterial having pores smaller than 2 nm in diameter and macroporousmaterial as a material having pores larger than 50 nm in diameter.

Mesoporous materials may include various types of silica and aluminathat have similarly sized mesopores. Mesoporous oxides of niobium,tantalum, titanium, zirconium, cerium and tin have been researched andreported. Of all the variants of mesoporous materials, mesoporouscarbon, such as carbons and carbon-based materials have voids, orifices,pathways, conduits or the like having at least one mesoporous dimension,has achieved particular prominence, having direct applications in energystorage devices. Mesoporous carbon can be defined as having porositywithin the mesopore range, and this significantly increases the specificsurface area. Another common mesoporous material is activated carbon,referring to a form of carbon processed to have small, low-volume poresthat increase the surface area. Activated carbon, in a mesoporouscontext, is typically composed of a carbon framework with bothmesoporosity and microporosity, such as depending on the conditionsunder which it was synthesized. According to IUPAC, a mesoporousmaterial can be disordered or ordered in a mesostructure. In crystallineinorganic materials, mesoporous structure noticeably limits the numberof lattice units, and this significantly changes the solid-statechemistry. For example, the battery performance of mesoporouselectroactive materials is significantly different from that of theirbulk structure.

The carbon-based particle 100A is nucleated and grown in an atmosphericplasma-based vapor flow stream of reagent gaseous species such asmethane (CH₄) to form an initial carbon-containing and/or carbon-basedparticle without specifically or explicitly requiring a separatestand-alone initial seed particle around which carbon structures aresubsequently grown, as seen in conventional techniques. An initialcarbon-based synthesized particle independent of a separate seedparticle pursuant to the presently disclosed embodiments can then beexpanded:

-   -   in-flight, describing the systematic coalescence pursuant to        nucleation and/or growth from an initial carbon-based homogenous        nucleation independent of a seed particle of additional        carbon-based material derived from incoming carbon-containing        gas mid-air within a microwave-plasma reaction chamber; or,    -   by being grown and/or deposited directly onto a supporting or        sacrificial substrate, such as a current collector, within a        thermal reactor.        Coalescence implies a process in which two phase domains of the        same composition come together and form a larger phase domain.        Alternatively put, the process by which two or more separate        masses of miscible substances seem to pull each other together        should they make the slightest contact. The carbon-based        particle 100A, may be alternatively referred to as just        particle, and/or by any other similar term. The term mesoporous,        as both generally understood and as used herein, may be defined        as a material containing pores with diameters between 2 and 50        nm, according to International Union of Pure and Applied        Chemistry (IUPAC) nomenclature.

Synthesis and/or growth of carbon-based particle 100A within a reactionchamber in and/or otherwise associated with a microwave-based reactor,such as a reactor is disclosed by Stowell, et al., “Microwave ChemicalProcessing Reactor”, U.S. Pat. No. 9,767,992, filed on Sep. 19, 2017,incorporated by reference herein in its entirety. Synthesis can occur insystems other than microwave reactors such as taking place in a thermalreactor, referring generally to a chemical reactor defined by anenclosed volume in which a temperature-dependent chemical reactoroccurs.

The carbon-based particle 100A, also shown as a carbon-based particle100D in FIG. 1D, is synthesized as so described herein with athree-dimensional (3D) hierarchical structure comprising short range,local nano-structuring in combination with long range approximatefractal feature structuring, which in this context refers to theformation of successive layers positioned orthogonally to each other.Orthogonally here is defined as involving the 90-degree rotation of eachsuccessive layer relative to the one beneath it, and so on and so forth,allowing for the creation of vertical, or substantially vertical, layersand/or intermediate layers.

Contiguous microstructures 107E suitable for incorporation within anelectrochemical cell cathode for lithium-sulfur (Li S) secondary systemsare shown in FIG. 1E, which itself shows an enlarged and more detailedview of the hierarchical pores 101A shown in FIGS. 1A and 1D. In someimplementations, contours and shapes of the contiguous microstructures107E can structurally define the open porous scaffold 102A, as shown inFIG. 1A, with diffusion pathways 109E, which are suitable for Li iontransport from the anode to the cathode during discharge-charge cycles.The contiguous microstructures 107E can include:

-   -   microporous frameworks, such as the diffusion pathways 109E,        defined by a dimension 101E of >50 nm that provide tunable Li        ion conduits; mesoporous channels defined by a dimension 102E of        about 20 nm to about 50 nm (generally defined under IUPAC        nomenclature and referred to as mesopores or mesoporous) that        act as Li ion-highways for rapid Li ion transport therein; and        microporous textures, such as pores 105E, defined by a dimension        103E of <4 nm for charge accommodation and/or active material,        such as sulfur (S) in Li S systems, confinement.

A hierarchical porous network 100E including the diffusion pathways109E, in addition to providing pores 105E for confining active materialand defining pathways for ion transport, can be configured to define thecontiguous microstructures 107E for providing active Li intercalatingstructures. Accordingly, the hierarchical porous network 100E of thecarbon-based particle 100D can be implemented in either an anode or acathode or, for example, a Li ion or a Li S battery system with aspecific capacity rated at between about 744 mAh/g to about 1,116 mAh/g.For either Li ion or Li S configurations, Li can infiltrate open porousscaffold, such as when provided by molten Li metal via capillaryinfusion, to at least partially chemically react with exposed carbontherein in reactive systems.

One or more physical, electrical, chemical and/or material properties ofthe carbon-based particle 100A may be defined during its synthesis.Also, dopants, referring to traces of impurity element that isintroduced into a chemical material to alter its original electrical oroptical properties, such as Si, SiO, SiO2, Ti, TiO, Sn, Zn, and/or thelike. may be dynamically incorporated during synthesis of thecarbon-based particle 100A to at least in part affect materialproperties including electrical conductivity, wettability, and/or ionconduction or transport through the hierarchical porous network 100E.Microporous textures having dimension 103E and/or hierarchical porousnetwork 100E more generally may be synthesized, prepared, or created toinclude smaller pores for chemical, such as sulfur (S),micro-confinement, the smaller pores being defined as ranging from 1 to3 nm. Also, each graphene sheet, such as shown in FIG. 1C, may rangefrom 50 to 200 nm in diameter (L_(a)).

The open porous scaffold 102A may be synthesized independent of abinder, such as a traditional, nonconductive polymer binder typicallyused in conjunction with and a conductive additive onto a metal foilcurrent collector in battery end-use applications. Traditionalconfigurations involving usage of a binder can lead toelectronic/current conduction-related or ionic constrictions and poorcontacts due to randomly distributed conductive phases. Moreover, whenhigh-capacity electrode materials are employed, relatively high physicalstress generated during electrochemical reactions can disrupt mechanicalintegrity of traditional binder systems, therefore, in turn, reducingcycle life of batteries.

A vapor flow stream used to synthesize the carbon-based particle 100A,or the carbon-based particle 100D, which is or can be identical to thecarbon-based particle 100A, may be at least flowed in part into avicinity of a plasma, such as that generated and/or flowed into areactor and/or chemical reaction vessel. Such a plasma reactor may beconfigured to propagate microwave energy toward the vapor flow stream toat least in part assist with synthesis of carbon-based particle 100A,may involve carbon-particle based and/or derived nucleation and growthfrom constituent carbon-based gaseous species, such as methane (CH₄),where such nucleation and growth may substantially occur from aninitially formed carbon-based homogenous nucleation independent of aseed particle within a reactor. Such a reactor accommodates control ofgas-solid reactions under non-equilibrium conditions, where thegas-solid reactions may be controlled at least in part by any one ormore of:

-   -   ionization potentials and/or thermal energy associated with        constituent carbon-based gaseous species introduced to the        reactor for synthesis of the carbon-based particle; and/or    -   kinetic momentum associated with the gas-solid reactions.        The vapor flow stream may be flowed into a reactor and/or        reaction chamber for the synthesis of carbon-based particle 100A        at substantially atmospheric pressure. And change in wettability        of carbon-based particle 100A and/or any constituent members        such as open porous scaffold 102A at least in part may involve        adjustment of polarity of a carbon matrix associated with        carbon-based particle 100A.        Procedures for Synthesis        Microwave Reactor

A vapor flow stream including carbon-containing constituent species,such as methane (CH₄), may be flowed into one of two general reactortypes to produce the carbon-based particle 100A:

-   -   a thermal reactor; or,    -   a microwave-based reactor. Suitable types of microwave reactors        are disclosed by Stowell, et al., “Microwave Chemical Processing        Reactor”, U.S. Pat. No. 9,767,992 files on Sep. 19, 2017,        incorporated herein by reference in its entirety.

The term in-flight implies a novel method of chemical synthesis based oncontacting particulate material derived from inflowing carbon-containinggaseous species, such as those containing methane (CH₄), to crack suchgaseous species. Cracking, as generally understood and as referred toherein, implies the technical process of methane pyrolysis to yieldelemental carbon, such as high-quality carbon black, and hydrogen gas,without the problematic contamination by carbon monoxide, and withvirtually no carbon dioxide emissions. A basic endothermic reaction thatmay occur within a microwave reactor to create the carbon-based particle100A is shown as equation (7) below:CH₄+74.85 kJ/mol→C+2H₂  (7)

Carbon derived from the above-described cracking process and/or asimilar or a dissimilar process may fuse together while being dispersedin a gaseous phase, referred to as in-flight, to create carbon-basedparticles, structures, substantially 2D graphene sheets, 3Dagglomerations, and/or pathways defined therein, including:

interconnected 3D agglomerations 101B of multiple layers of graphenesheets 101C and/or single layer graphene as schematically depicted inFIG. 1C, that are fused together to form the open porous scaffold 102Athat facilitates electrical conduction along and across contact pointsof the graphene sheets 101C, which, as shown in FIG. 1B, may includeand/or refer to 5 to 15 layers of few-layer graphene that are orientedin a stacked configuration to have a vertical height referred to as astack height (L_(c)); and, any one or more of the contiguousmicrostructures 107E interspersed with or otherwise defined in shape bythe interconnected 3D agglomerations 101B; in some configurations, theinterconnected 3D agglomerations can be prepared to comprise one or moreof single layer graphene (SLG), few layer graphene (FLG) defined asranging from 5 to 15 layers of graphene, or many layer graphene (MLG).

As introduced earlier, interconnected 3D agglomerations of multiplelayers of graphene sheets 101B orthogonally fused together to serve as atype of intrinsic, self-supporting, binder or joining material allowingfor the elimination of a separate traditional binder material. Suchprocedures are substantially different from conventional sintering, orfrittage, as commonly understood and as referred to herein, whichimplies the process of compacting and forming a solid mass of materialby heat or pressure without melting it to the point of liquefactionwhere materials are bonded at specific acute angles to one-another.

Few layer graphene (FLG), defined herein as ranging from 5 to 15 layersor sheets of graphene, are fused at an angle that is not flat relativeto other FLG sheets to nucleate and/or grow at an angle and thereforeself-assemble over time. Moreover, process conditions may be tuned toachieve synthesis, nucleation, and/or growth of the carbon-basedparticle 100A, also referring to a plurality of carbon-based particles,on a component and/or a wall surface within a reaction chamber, orentirely in-flight upon contact with other carbon-based materials.

Electrical conductivity of deposited carbon and/or carbon-basedmaterials may be tuned by adding metal additions into the carbon phasein the first part of the deposition phase or to vary the ratios of thevarious particles discussed. Other parameters and/or additions may beadjusted, as a part of an energetic deposition process, such that thedegree of energy of deposited carbon and/or carbon-based particles willeither:

-   -   bind together; or,    -   not bind together.

By nucleating and/or growing the carbon-based particle 100A in anatmospheric plasma-based vapor flow stream either in-flight or directlyonto a supporting or sacrificial substrate, a number of the steps andcomponents found in both traditional batteries and traditionalbattery-making processes can be eliminated. Also, a considerable amountof tailoring and tunability can be enabled or otherwise added into thediscussed carbons and/or carbon-based materials.

For instance, a traditional battery may use a starting stock of activematerials, graphite, etc., which may be obtained as off-the-shelfmaterials to be mixed into a slurry. In contrast, the carbon-basedparticle 100A disclosed herein may enable, as a part of the carbon orcarbon-based material synthesis and/or deposition process, tailoringand/or tuning the properties of materials, in real-time, as they arebeing synthesized in-flight and/or deposited onto a substrate. Thiscapability presents a surprising, unexpected, and substantial favorabledeparture from that currently available regarding creation ofcarbon-based scaffolded electrode materials in the secondary batteryfield.

Reactor and/or reactor design of that disclosed by Stowell, et al.,“Microwave Chemical Processing Reactor”, U.S. Pat. No. 9,767,992 filedon Sep. 19, 2017, may be adjusted, configured and/or tailored to controlwanted or unwanted nucleation sites on internal surfaces of reactionchambers exposed to carbon-based gaseous feedstock species, such asmethane (CH₄). In-flight particles qualities may be influenced by theirsolubility in the gaseous species in which they are flowed in such thatonce a certain energy level is achieved, it is conceivable for carbon tocrack off, as described by thermal cracking, and form its own solid in amicrowave reactor.

Adjusting for Unwanted Carbon Accumulation on Reaction Chamber Walls

Moreover, tuning of disclosed reactors and related systems may beperformed to both proactively, such as prior to the observation ofundesirable process conditions, and reactively, such as after suchconditions are observed, address issues associated with carbon-basedmicrowave reactor clogging. For instance, open surfaces, feed holes,hoses, piping, and/or the like may accumulate unwanted carbon-basedparticulate matter as a by-product of synthetic procedures performed tocreate carbon-based particle 100A. A central issue observed in amicrowave reactor may include this tendency to experience clogging inand/or along orifices, the reason being related to walls and othersurfaces exposed to in-flowing gaseous carbon-containing species havingcarbon solubility as well. Therefore, is it possible to unwantedly growon the walls of a reaction chamber and/or on the exit tube. Over time,those growths will extend out and ultimately impinge flow and can shutdown chemical reactions occurring within the reactor and/or reactionchamber. Such a phenomena may be akin to tube, such as an exhaust, wallbuild-up of burnt oil in a high-performance or racing internalcombustion engine, where, instead of burning, such as combusting,fossil-fuel based gasoline, methane is used to result in the unwanteddeposit of carbon on reaction chamber wells since metal inside thereaction chamber itself has a carbon solubility level.

Although methane is primarily used to create carbon-based particle 100A,any carbon-containing and/or hydrocarbon gas, like C₂ or acetylene orany one or more of: C₂H₂, CH₄, butane, natural gas, biogas, such as thatderived from decomposition of biological matter, will likewise functionto provide a carbon-containing source.

The described uncontrolled and unwanted carbon growth within exposedsurfaces of a microwave reactor may be compared to that occurring withinan internal combustion engine exhaust manifold, as opposed to thecylinder bore, of the engine, especially where the plume of plasma, suchas hot and excited gas about to enter into the plasma phase, is at theonset of the manifold, and burnt gas and carbon-based fragments aretraveling down and plugging-up flow through the manifold, cross-pipes,and catalytic converter, and exit-pipes. Process conditions maytherefore be proactively tuned to adjust and therefore accommodate forpotential carbon-build-up in the microwave reactor, which relies on thepresence of a plasma for hydrocarbon gas cracking. To maintain thisplasma, a certain set of conditions must be maintained, otherwiseback-pressure accumulation can destroy the plasma prior to its creationand subsequent ignition, etc.

Thermal Reactor

In the alternative or addition to synthesis of carbon-based particle100A in a microwave reactor, structured carbons can be created bythermally cracking hydrocarbons by heat application in a reactor, suchas a thermal reactor. Example configurations may include exposure ofincoming carbon-based gaseous species, such as any one or more of theaforementioned hydrocarbons, to a heating element, similar to a wire ina lightbulb.

The heating element heats up the inside of a reaction chamber whereincoming carbon-containing gas is ionized. The carbon-containing gas isnot burnt, due to the absence of sufficient oxygen to sustaincombustion, but is rather ionized from contact with incoming thermalradiation, such as in the form of heat, to cause nucleation ofconstituent members of carbon-based particle 100A, and ultimatelysynthesize, via nucleation, carbon-based particle 100A, and/orcarbon-based particles similar to it, in its entirety. In thermalreactors, at least some of the observed nucleation of carbon-basedparticles can occur on walls or on the heating element itself.Nevertheless, particles can still nucleate which are small enough to becracked by the speed of flowing gas, where such particles are capturedto assist in the creation of carbon-based particle 100A.

Cracked carbons can be used to create a multi-shell fullerene carbonnano-onion (CNO), and/or other fullerenes, and smaller fractions ofcarbons with fullerene internal crystallography. In comparing synthesisof carbon-based particle 100A via microwave and thermal reactors, thefollowing distinctions have been observed:

-   -   microwave reactors can provide tuning capabilities suitable to        provide a broader range of allotropes of carbon; whereas,    -   thermal reactors tend to allow for the fine-tuning of process        parameters, such as heat flow, temperature, and/or the like, to        achieve the needs of specific end-use application targets of        carbon-based particle 100A.

For instance, thermal reactors are currently being used to build Li Selectrochemical cell electrodes, such as anodes and cathodes. Typicaltreatment process temperatures range in the thousands of Kelvins, toproduce the carbon-based particle 100A and/or carbon-based aggregatesassociated therewith, when compressed, have an electrical conductivitygreater than 500 S/m, or greater than 5,000 S/m, or from 500 S/m to20,000 S/m. Optimal performance has been observed at between 2,000-4,000K.

Carbon-Based Particle-Physical Properties & Implementation in Li Ion andLi S Batteries

Any of the carbon-based structures shown in FIG. 1A-1F may beincorporated into a secondary battery electrode, such as that of alithium (Li) ion battery, as substantially set forth in U.S. Patent Pub.No. 2019/0173125, published on Jun. 6, 2019, incorporated by referenceherein in its entirety. Disclosed implementations typically relate to Liincorporation or infusion within the anode, although carbon-basedsystems can be revised for compatibility and integration with thecathode, especially in Li S systems where microconfinement of S isdesirable to mitigated unwanted polysulfide (PS) shuttle and cellself-discharge.

Particulate carbon contained in and/or otherwise associated withcarbon-based particle 100A may be implemented in a Li ion battery anodeor cathode as a structural and/or electrically conductive material andbe characterized by hierarchical porous network 100E with a widedistribution of pore sizes, also referred to as a multi-modal pore sizedistribution. For example, particulate carbon can contain multi-modaldistribution of pores in addition or in the alternative to thecontiguous microstructures 107E, as shown in FIG. 1E, that at least inpart further define open porous scaffold 102A with one or more thediffusion pathways 109E. Such pores may have sizes from 0.1 nm to 10 nm,from 10 nm to 100 nm, from 100 nm to 1 micron, and/or larger than 1micron. Pore structures can contain pores with a multi-modaldistribution of sizes, including smaller pores, with sizes from 1 nm to4 nm, and larger pores, with sizes from 30 to 50 nm. Such a multi-modaldistribution of pore sizes in carbon-based particle 100A can bebeneficial in Li S battery system configurations, where S-containingcathodes in Li S batteries can be confined in the pores 105E having thedimension 103E of approximately less than 1.5 nm or in the range 1 to 4nm in size. Control of saturation and crystallinity of S and/or ofgenerated S compounds in a carbon-based cathode including the contiguousmicrostructures 107E in larger pores or pathways ranging from 30 to 50nm in size, or pores greater than twice the size of solvated lithiumions (such as lithium, Li, ions 108E), can enable and/or facilitaterapid diffusion, or, mass transfer, of solvated Li ions in the cathode.

As introduced earlier, the lithium-sulfur battery, abbreviated as a Li—Sbattery, is a type of rechargeable battery, notable for its highspecific energy. A Li—S battery, can include sulfur (S) infiltrated orinfused for confinement within the pores 105E and along exposed surfacesof the contiguous microstructures 107E of mesoporous particle 100D.Accordingly, S can infiltrate the open porous scaffold 102A, whenincorporated into a cathode of a Li S battery, to deposit on internalsurfaces of the carbon-based particle 100A, 100D and/or within thecontiguous microstructures 107E, as shown in FIG. IE and by schematic100F shown in FIG. 1F, which shows intermediate steps associated withthe reduction of sulfur to the sulfide ion (S²⁻).

Carbon-Based Particle-Formed to Address Polysulfide (PS)-RelatedChallenges

Seeking to address at least some of the challenges associated with suchpolysulfide (PS) systems, carbon-based particle 100A and cathodic activematerial form a meta-particle framework, where cathodic electroactivematerials, such as elemental sulfur that may form PS compounds 100F asshown in FIG. 1F, are arranged within carbon pores/channels, such aswithin any one or more of the contiguous microstructures 107E, as shownin FIG. 1E, including pores 104E, 105E, and/or pathways 106E and/or thediffusion pathways 109E. S can be, for example, substantiallyincorporated within the contiguous microstructures 107E at a loadinglevel that represents 35-100% of the total weight/volume of activematerial in carbon-based particle 100A and/or 100E overall.

This type of organized particle framework can provide a low resistanceelectrical contact between the insulating cathodic electroactivematerials, such as elemental S, and the current collector whileproviding relatively high exposed surface area structures that arebeneficial to overall specific capacity and that may assist Li ionmicro-confinement as enhanced by the formation of Li S compoundstemporarily retained in the contiguous microstructures 107E, such as inthe pores 105E, to in turn control and direct migration of Li ions asmay be related to electric current conduction in a battery electrodeand/or system. Implementations of carbon-based particle 100A can alsobenefit cathode, as well as anode, stability by trapping at least someportion of any created polysulfides by using tailored structures, suchas that shown by the contiguous microstructures 107E, to activelyprevent them from unwantedly migrating through electrolyte to the anoderesulting in unwanted parasitic chemical reactions associated withbattery self-discharge.

Migration of Polysulfides (PS) during Li S Battery System Usage

As introduced earlier, with reference to PS shuttle mechanisms observedin Li S battery electrodes and/or systems, PS dissolve very well inelectrolytes. This causes another Li—S cell characteristic, the shuttlemechanism. The PS S_(n2)—that form and dissolve at the cathode, diffuseto the Li anode and are reduced to Li₂S₂ and Li₂S. The PS species S_(n)²⁻ that form at the cathode during discharging dissolve in theelectrolyte there. A concentration gradient versus the anode develops,which causes the PS to diffuse toward the anode. Step by step, the PSare distributed in the electrolyte. Subsequent high-order PS speciesreact with these compounds and form low-order polysulfides S_((n-x)).This means that the desired chemical reaction of sulfur at the cathodepartly also takes place at the anode in an uncontrolled fashion, whereboth chemical and electrochemical reactions are conceivable, whichnegatively influences overall cell characteristics.

If low-order PS species form near the anode, they diffuse to thecathode. When the cell is discharged, these diffused species are furtherreduced to Li₂S₂ or Li₂S. As a result, the cathode reaction partly takesplace at the anode during the discharging process or, rather, the cellself-discharges. Both are undesirable effects decreasing specificcapacity. In contrast, the diffusion to the cathode during the chargingprocess is followed by a re-oxidation of the PS species from low orderto high order. These PS then diffuse to the anode again. This cycle isgenerally known as the shuttle mechanism, which can be very pronounced,it is possible that a cell can accept an unlimited charge to bechemically short-circuited. In general, the shuttle mechanism causes aparasitic sulfur active matter loss. This is due to the uncontrolledseparation of Li₂S₂ and Li₂S outside of the cathode area and iteventually causes a considerable decrease in cell cycling capability andservice life. Further aging mechanisms can be an inhomogeneousseparation of Li₂S₂ and Li₂S on the cathode or a mechanical cathodestructure breakup due to volume changes during cell reaction.

Pores of Carbon-Based Particle Confine Sulfur and Prevent PS Shuttle tothe Anode

To address the phenomenon of PS shuttling, any one or more of thecontiguous microstructures 107E of carbon-based particle 100A in acathode can provide a region formed with an appropriate dimension, suchas the pores 105E having the dimension 103E of less than 1.5 nm, todrive the creation of lower order polysulfides, such as S and Li₂S, andtherefore prevent the formation of the higher order solublepolysulfides, Li_(x)S_(y) with y greater than 3, that facilitate Lishuttle, such as loss to the anode. As described herein, the structureof the particulate carbon and the cathode mixture of materials can betuned during particulate carbon formation within a microwave plasma orthermal reactor. In addition, cathodic electroactive materials, such aselemental sulfur, solubility and crystallinity in relation to Li phaseformation, can be confined/trapped within the micro- and/or meso-porousframework of the contiguous microstructures 107E of carbon-basedparticle 100A.

A multi-modal distribution of pore sizes can be indicative of structureswith high surface areas and a large quantity of small pores that areefficiently connected to the substrate and/or current collector viamaterial in the structure with larger feature sizes to provide moreconductive pathways through the structure. Some non-limiting examples ofsuch structures are fractal structures, dendritic structures, branchingstructures, and aggregate structures with different sized interconnectedchannels composed of pores and/or particles that are roughly cylindricaland/or spherical.

Example particulate carbon materials used in the Li ion or Li Sbatteries described herein are described in U.S. Pat. No. 9,997,334,entitled “Seedless Particles with Carbon Allotropes,” which is assignedto the same assignee as the present application, and is incorporatedherein by reference. The particulate carbon materials can containgraphene-based carbon materials that include a plurality of carbonaggregates, each carbon aggregate having a plurality of carbonnanoparticles, each carbon nanoparticle including graphene, optionallyincluding multi-walled spherical fullerenes, and optionally with no seedparticles such as with no nucleation particle. In some cases, theparticulate carbon materials are also produced without using a catalyst.The graphene in the graphene-based carbon material has up to 15 layers.A ratio of carbon to other elements, except hydrogen, in the carbonaggregates is greater than 99%. A median size of the carbon aggregatesis from 1 micron to 50 microns, or from 0.1 microns to 50 microns. Asurface area of the carbon aggregates is at least 10 m²/g, or is atleast 50 m²/g, or is from 10 m²/g to 300 m²/g or is from 50 m²/g to 300m²/g, when measured using a Brunauer-Emmett-Teller (BET) method withnitrogen as the adsorbate. The carbon aggregates, when compressed, havean electrical conductivity greater than 500 S/m, or greater than 5,000S/m, or from 500 S/m to 20,000 S/m.

Distinctions between the Carbon-Based Particles and ConventionalTechnology

Conventional composite-type Li-ion or Li S battery electrodes may befabricated from a slurry cast mixture of active materials, includingconductive additives such as fine carbon black and graphite for usage ina battery cathode at a specific aspect ratio, and polymer-based bindersthat are optimized to create a unique self-assembled morphology definedby an interconnected percolated conductive network. While, inconventional preparations or applications, additives and binders can beoptimized to improve electrical conductivity there-through by, forexample, offering lower interfacial impedance and thereforecorrespondingly yield improvements in power performance and delivery,they represent a parasitic mass that also necessarily reduces specific,also referred to as gravimetric, energy and density, an unwanted endresult for current demanding high-performance battery applications.

To minimize losses due to parasite mass, such as that caused byincreased active and/or inactive ratio, and concurrently enable fasteraccess of electrolyte to the complete surface of an electrode, thediffusion pathways 109E may be re-oriented to effectively shorten Li iondiffusion path lengths for charge transfer. The hierarchical pores 101Aand/or the open porous scaffold 102A may be created from reduced-sizecarbon particles and/or active materials down to nanometer scales. Theexternal specific surface area (SSA), defined as the total surface areaof a material per unit of mass, with units of m²/kg or m²/g, or solid orbulk volume (units of m²/m³ or m⁻¹) is a physical value of any one ormore of the presently disclosed carbon particles that can be used todetermine the type and properties of a material. For instance, the SSAof a sphere increases with decreasing diameter. However, as the particlesize is decreased down into the nanometer size range there areassociated attractive van der Waal forces that can impede dispersion,facilitate agglomeration, and thereby increase cell impedance and reducepower performance.

Another approach to shortening ion diffusional pathways, referring tothe diffusion pathways 109E shown in FIG. 1E, is to uniquely engineerthe internal porosity of the constitutive carbon-based particles, suchas those created by the agglomerations 101B to create the contiguousmicrostructures 107E. A surface curvature can be referred to as a poreif its cavity is deeper than it is wide. As a result, this definitionnecessarily excludes many nanostructured carbon materials where just theexternal surface area is modified, or in close packed particles wherevoids, such as intra-particular spaces or regions, are created betweenadjacent particles, as in the case of a conventional slurry castelectrode.

With respect to the engineering, referring to the synthesis, creation,formation, and/or growth of carbon-based particle 100A either in-flightin a microwave-based reactor or via layer-by-layer deposition in athermal reactor as substantially described earlier, reactor processparameters may be adjusted to tune the size, geometry, and distributionof hierarchical pores 101A and/or the contiguous microstructures 107Ewithin carbon-based particle 100A. Hierarchical pores 101A and/or thecontiguous microstructures 107E within carbon-based particle 100A may betailored to achieve performance figures particularly well-suited forimplementation in high-performance fast-current delivery devices, suchas supercapacitors.

As generally described earlier, a supercapacitor (SC), also called anultracapacitor, is a high-capacity capacitor with a capacitance valuemuch higher than other capacitors, but with lower voltage limits, thatbridges the gap between electrolytic capacitors and rechargeablebatteries. It typically stores 10 to 100 times more energy per unitvolume or mass than electrolytic capacitors, can accept and delivercharge much, much faster than batteries, and tolerates many more chargeand discharge cycles than rechargeable batteries.

In many of the available off-the-shelf commercial carbons used in earlysupercapacitor development efforts, there were worm-like narrow poreswhich became a bottleneck or liability when operating at high currentdensities and fast charge- and discharge rates, as electrons mayencounter difficulty in flow through, in or around such structures orpathways. Even though pore dimensions were fairly uniform but stilladjustable to accommodate a wide range of length scales, real-lifeachievable performance was still self-limited, as based on thestructural challenges inherent to the worm-like narrow pores.

Compared to conventional porous materials with uniform pore dimensionsthat are tuned to a wide range of length scales, the presently disclosed3D hierarchical porous materials, such as that shown by hierarchicalpores 101A and/or the contiguous microstructures 107E withincarbon-based particle 100A, may be synthesized to have well-defined poredimensions, such as the contiguous microstructures 107E including pores104E, 105E, and/or pathways 106E and/or the diffusion pathways 109E andtopologies to overcome the shortcomings of conventional mono-sizedporous carbon particles by creating multi-modal pores and/or channelshaving the following dimensions and/or widths:

-   -   meso (2 nm<d_(pore)<50 nm) pores;    -   macro (d_(pore)>50 nm) pores 201A to minimize diffusive        resistance to mass transport; and,    -   micro (d_(pore)<2 nm) pores 202 to increase surface area for        active site dispersion and/or ion storage, capacitance relating        to density and number of ions that can be stored within a given        pore size, such as that shown by the pore 105E having the        dimension 103E in FIG. 1E.

Although no simple linear correlation has been experimentallyestablished between surface area and capacitance, the carbon-basedparticle 100A provides optimal micropore size distributions and/orconfigurations that are different for each intended end-use applicationand corresponding voltage window. To optimize capacitance performance,the carbon-based particle 100A may be synthesized with very narrow poresize distributions (PSD); and, as desired or required voltages areincreased, larger pores are preferred. Regardless, currentstate-of-the-art supercapacitors have provided a pathway to engineeringthe presently disclosed 3D hierarchical structured materials forparticular end-use applications.

In supercapacitors, capacitance and power performance is primarilygoverned by, for example:

-   -   surface area of the pore wall;    -   size of pore; and    -   interconnectivity of the pore channels, which affects electric        double layer performance.

In contrast, Li ion and/or Li—S storage batteries undergo faradaicreduction/oxidation reactions within the active material and thereby mayneed many of the Li ion transport features of a supercapacitor, such asefficiently oriented and/or shortened Li ionic diffusion pathways.Regardless, in any application, including a supercapacitor as well as atraditional Li ion or Li S secondary battery, a 3D nanocarbon-basedframework/architecture, such as that defined open porous scaffold 102A,can provide continuous electrical conducting pathways, such as acrossand along electrically conductive interconnected agglomerations ofgraphene sheets 101B, alongside, for example, highly-loaded activematerial having high areal and volumetric specific capacity.

Carbon-Based Particle Used as a Formative Material for a Cathode

To address prevailing issues with relatively low electrical and ionicconductivities, volume expansion and polysulfide (PS) dissolution incurrent Li S cathode electrode designs, the carbon-based particle 100Ahas the hierarchical pores 101A and/or the contiguous microstructures107E formed therein to define the open porous scaffold 102A, whichincludes the pores 105E with microporous textures having the dimension103E, such as approximately less than 1.5 nm or 1-4 nm cavities suitableto confine elemental sulfur and/or Li S related compounds. The openporous scaffold 102A, while confining sulfur, also provides a hostscaffold-type structure to manage S expansion to ensure electronconduction across the sulfur-carbon (S—C) interface, such as at contactand/or interfacial regions of S and C within the pores 105E by, forexample, tailored in-situ nitrogen (N) doping of the carbon (C) withinthe reactor. Confining S within a nanometer (nm) scale cavity, such aspores 105E with microporous textures 103E, favorably alters both:

-   -   the equilibrium saturation, such as the solubility product; and,    -   crystalline behavior of S, such that S remains confined as may        be necessary for desirable electrical conduction upon        dissociation of Li S compounds, etc. within microporous textures        or the pores 105E having the dimension 103E, with no external        driving force required to control unwanted PS migration to the        anode electrode.        As a result, the dimension 103E of the pores 105E results in no        need for separators that attempt to impede polysulfide (PS)        diffusion while, at the same time, negatively impacting cell        impedance, such as the effective resistance of an electric        circuit or component to alternating current, arising from the        combined effects of ohmic resistance and reactance, and        polarization. By using carbon with optimum, relative to        elemental S, Li and/or Li S micro-confinement, and non-optimum        multi-modal, referring to the contiguous microstructures 107E        including pores 104E, 102E, and/or 103E, or (alternatively)        bi-modal pore distributions, the carbon-based particle 100A        demonstrates operation of the principle of micro-confinement in        properly optimized structures.

Such optimized structures include incorporation with the agglomerations101B, which can themselves be prepared to include parallel stackedgraphene layers, such as that produced from graphite having strong (002)dimensionality to random few-layer (FL) graphene with nanoscopic poreshaving low (002) dimensionality. FIGS. 1G and 1H show systematicintercalation of Li ions in carbon lattices and structures, beingpositioned within individual graphene layer cells in FIG. 1G, andin-between adjacent and parallel graphene layers in FIG. 1H. Theconfigurations shown in FIG. 1H can include multiple stages, includingStages 1 through 3, each state representing various dimensions andspacing levels of graphite layer planes to yield a theoretic specificcapacity of approximately 372 mAh/g at the cathode, or more.

FIG. 2 shows an evolution beyond conventional adjacent stacked FLgraphene layers shown in Stages 1 to 3 in FIG. 1H, where cavities areformed extending depth-wise into several of the adjacent stacked FLgraphene layers, each layer having tunable D-spacing ranging fromapproximately 3.34 Å to 4.0 Å, or 3 Å to 20 Å. Accordingly, Li ions canbe intercalated between adjacent graphene layers as well as forming alayer on exposed surfaces of the cavity, also referred to as ananoscopic pore, to yield a specific capacity range in excess of 750mAh/g. When viewed collectively, an example enlarged section of the 3Dself-assembled binder-less carbon-based particle can coalesce to form acarbon-based network, lattice, scaffold, or particle, which may includeany one or more of the presently disclosed carbon-based structures shownin FIG. 1A through FIG. 1E, according to some implementations. Thecarbon-based network can include any one or more of a plurality ofmacropores or micropores 202.

The carbon-based particle 100A also provides the ability to effectivelyload or infuse carbon scaffold 300 shown in FIG. 3 with elemental Li,such as that provided from molten Li metal or a vapor derivativethereof. The carbon scaffold 300 can be created in-reactor by either:

-   -   layer-by-layer deposition of multiple carbon-based particles        100A by a slurry-case method; or,    -   by a continuous sequence of a group of plasma spray-torches, as        shown by plasma spray-torch system 400B in FIG. 4B, with sulfur,        such as elemental sulfur.

For Li S battery performance to reliably exceed conventional Li ionbatteries, industry-scalable techniques must achieve high S loading,such as >70% sulfur per unit volume, relative to all additives andcomponents of a given cathode template, while maintaining the nativespecific capacity of the S active material. Attempts to incorporate Sinto a cathode host, such as by any one-off, performed independently orin any combination: electrolysis, wet chemical, simple mixing, ballmilling, spray coating, and catholytes, have either not fullyincorporated the S as desirable, or are otherwise not economicallyscalable or manufacturable.

Unlike melt infiltration where small pores are thermodynamicallyinaccessible, presently disclosed synthetic approaches can use anisothermal vapor technique, introduced and reacted at substantiallyatmospheric pressure, where the high surface free energy of nanoscalepores or surfaces drives the spontaneous nucleation of sulfur containingliquids until a conformal coating of sulfur and/or lithium-containingcondensate is reached on inner-facing surfaces of hierarchical pores101A and/or the contiguous microstructures 107E. In essence, uniquevapor infusion process infuses sulfur into fine pores, such as any oneor more of hierarchical pores 101A and/or the contiguous microstructures107E and/or pores 104E, 105E and/or pathways 106E and/or the diffusionpathways 109E at the core of carbon-based particle 100A, and thereforenot just at its surface.

Carbon-Based Particles used to Create an Electrically ConductiveScaffold

Carbon-based particle 100A, may be fabricated any number of ways usingboth known and novel techniques disclosed herein, including:

-   -   slurry-casting, referring to conventional metalworking,        manufacturing and/or fabrication techniques in which a liquid        material is usually poured into a mold, which contains a hollow        cavity of the desired shape, and then allowed to solidify; or    -   a plasma spray-torch system 400B, such as that shown in FIG. 4B,        which may be used to perform layer-by-layer deposition to grow        carbon-based particle 100A incrementally.

Either technique as described above, or any other known or novelfabrication techniques, may be used to produce carbon scaffold 300,shown in FIG. 3 , in a graded manner. Control over the electricalgradients can result in the carbon scaffold 300 having varying degreesof electrical conductivity as dictated at least in part by any one ormore of electrical gradients and ionic conductive gradients, describedas follows:

electrical gradients can be defined by the graphene sheets 101Bsubstantially orthogonally fused together form the open porous scaffold102A, where electrical conduction occurs along and across contact pointsof graphene sheets 101B; and, ionic conductive gradients, such as Li iontransport, movement, or migration through the hierarchical pores 101Aand the contiguous microstructures 107E, can be benefited, in certainconfigurations of the carbon-based particle 100 by the effectiveshortening of the diffusion pathways 109E throughout thickness of thecarbon scaffold 300B in the vertical height direction A as shown in FIG.3B to, for example, permit Li ions intercalated between adjacentfew-layer graphene sheets, such as the graphene sheets 101B, to escapeand migrate toward a liquid electrolyte surrounding the carbon scaffold300B on route to the cathode curing electrochemical celldischarge-charge cycling.

Reference has been made throughout the presently disclosedimplementations to various forms of carbon synthesized in-flight withina reactor to create the graphene sheets 101B, which are interconnectedand conduct electricity along contact points and may vary in shape,size, position, orientation, and/or structure. Such variances can beinfluenced in differences in crystallinity and the particular type ofcarbon allotrope(s) used for creation of electrically conductiveinterconnected agglomerations of graphene sheets 101B. Crystallinityimplies the degree of structural order in a solid. In a crystal, atomsor molecules are arranged in a regular, periodic manner. The degree ofcrystallinity therefore has a significant influence on hardness,density, transparency, and diffusion.

Accordingly, the carbon-based particle 100 can be produced in the formof an organized scaffold, such as a carbon-based scaffold, out of areactor or be created during post-processing activities taking placeoutside of primary synthesis within a reactor.

Plasma processing and/or plasma-based processing, may be conductedwithin a reactor as disclosed by Stowell, et al., “Microwave ChemicalProcessing Reactor”, U.S. Pat. No. 9,767,992, issued on Sep. 19, 2017,where supply gas is used to generate a plasma in the plasma zone toconvert a process input material, such as methane and/or other suitablehydrocarbons in a gaseous phase, into separated components in a reactionzone to facilitate in-flight synthesis of carbon-based materials.

Alternative to synthesis by or within a microwave reactor as describedabove, thermal energy may be directed toward or near carbon-containingfeedstock materials supplied in a gaseous phase onto a sacrificialsubstrate 306 of the carbon scaffold 300 shown in FIG. 3 to sequentiallydeposit multiple layers of carbon-based particles 100A by, for example,plasma spray-torch system 400B shown in FIG. 4B. Such particles may beeither fused together in-flight, in a microwave reactor, or deposited,in a thermal reactor, in a controlled manner to achieve varyingconcentration levels of carbon-based particles 100A to therefore, inturn, achieve graded electrical conductivity proportionate toconcentration levels of carbon-based particles 100A in the carbonscaffold 300. Such procedures may be used to formulate porouscarbon-based electrode structure, such as carbon scaffold 300, that hasa high degree of tunability, such as in electrical conductivity andionic transport, while also eliminating many production steps andotherwise retaining a conventional outward appearance.

The open porous scaffold 102A can be produced with an open cellularstructure such that a liquid-phase electrolyte can easily infiltrateinto various pores, such as any one or more of the pathways, voids, andthe like of the contiguous microstructures 107E, therein. Skeletalportions of open porous scaffold 102A may be referred to as a matrix ora frame, and pores, such as hierarchical pores 101A and/or thecontiguous microstructures 107E, can be infiltrated with a fluid, liquidor gas, whereas skeletal material is usually formed as a solid material.

Porosity of the Carbon-Based Particle

A porous medium, such as carbon-based particle 100A, can becharacterized by its porosity. Other properties of the medium, such aspermeability, tensile strength, electrical conductivity, and tortuosity,may be derived from the respective properties of its constituents, ofsolid matrix and fluid interspersed therein, as well as media porosityand pore structure. Carbon-based particle 100A having the contiguousmicrostructures 107E interspersed throughout therein can be created outof a reactor to achieve desirable porosity levels that are conducive forLi ion diffusion. Related to such Li ion diffusion, the graphene sheets101B facilitate electron conduction along contact points thereof whilealso allowing for electrons to reunite with positive Li ions at reactionsites.

Regarding, porosity and tortuosity of open porous scaffold 102A ofcarbon-based particle 100A, an analogy may be made to marbles in a glassjar. Porosity, in this example, refers to spacing between the marblesthat allows liquid-phase electrolyte to penetrate into void spacesbetween the marbles, similar to the contiguous microstructures 107E thatdefine the diffusion pathways 109E within the carbon-based particle100A. The marbles themselves may be like swiss cheese, by allowingelectrolyte not only to penetrate in cracks between the graphene sheets101B, but also into each graphene sheet themselves, an individualgraphene sheet is shown in FIG. 1C. In this example as well as others,the relative shortening of the diffusion pathways 109E refers to howlong it takes Li ions infiltrated therein by, for example, capillaryaction to contact active material, such as S confined within pores 105E.The diffusion pathways 109E accommodate convenient and rapidinfiltration and diffusion of electrolyte, which may contain Li ions,into carbon-based particle 100A, which can then be grown or otherwisesynthesized further to create carbon scaffold 300 with graded electricconductivity.

The shortening of the diffusion pathways 109E refers toward theshortening of diffusion lengths through which Li ions move within openporous scaffold 102A in carbon scaffold 300 and not of the activematerial, such as S, itself confined within the pores 105E of thecontiguous microstructures 107E. This is on contrast to conventionaltechniques that require the diffusion length of the active material tobe shortened only by making the thickness of the active material lesseror smaller. The diffusion pathways 109E within the contiguousmicrostructures 107E can act as Li ion buffer reservoirs by controllingflow and/or transport of Li ions therein to provide a freer flowingstructure for Li ion transport therein, as may be beneficial for Li ionconfinement, as reacted with S coated on exposed carbon surfaces of thepores 105, and later Li ion transport during electrochemical cellcharge-discharge cycles. Transport of Li ions throughout the diffusionpathways 109E in the general directions shown in FIG. IE can take placein a liquid electrolyte initially infused and captured within openporous scaffold 102A, where such infusion of electrolyte occurs prior tocyclic carbon scaffold 300 usage in discharge-charge cycles.

Examples exist permitting for the initial diffusion and distribution ofliquid-phase electrolyte in open porous scaffold 102A of carbon-basedparticle 100A to fill up and occupy hierarchical pores 101A and/or thecontiguous microstructures 107E prior to usage of carbon scaffold 300,synthesized or otherwise created by layer-on-layer deposition ofcarbon-based particles 100A. Vacuum or air may also be used to fillhierarchical pores 101A and/or the contiguous microstructures 107E,which may allow or assist with wetting of electrolyte withcarbon-containing exposed surfaces within open porous scaffold 102A.

Li ions bounce from one location to another by a chain reaction, similarto the striking of newton balls, where one hits to result in forcetransference resulting in the movement of other balls. Similarly, eachLi ion moves a relatively short distance, yet remains able to move greatnumbers of Li ions in the collective through this type of chain reactionas described. The extent of individual Li ion movement may be influencedby the quantity of Li ions supplied altogether to carbon scaffold 300Bvia capillary infusion into open porous scaffold 102A, as may be thecrystallographic arrangement of Li ions and/or particles in, around, orwithin agglomerations of graphene sheets 101B.

Electrochemical Cell Anode or Cathode Created from Carbon Scaffold

The carbon scaffold 300, shown in FIG. 3 , can be integrated in batteryor supercapacitor applications, battery types including Li ion batteriesand Li S batteries. The carbon scaffold 300 can be incorporated intoeither the anode or the cathode for Li ion and Li S battery systems,although the contiguous microstructures 107E will need to be prepared toconfine S in the pores 105E or elsewhere to accommodate the creation andconfinement of polysulfides (PS) as well as the control of PS migration.An example battery system may include an electrochemical cell configuredto supply electric power to a system. The electrochemical cell may havean anode containing an anode active material, a cathode containing acathode active material, a porous separator disposed between the anodeand the cathode, and an electrolyte in ionic contact with the anodeactive material and the cathode active material.

The anode and cathode may include sacrificial substrate 306, that iselectrically conductive, with a first layer deposited there-upon as afirst contiguous film having a first concentration of carbon-basedparticles 100A shown as carbon-based particles 302 in FIG. 3 , such thata redundant description of the same is omitted.

A porous arrangement formed in the carbon scaffold 300 as defined by thecarbon-based particles 302, which are synonymous with and usedinterchangeably with multiple carbon-based particle 100A adjoinedtogether, and smaller carbon particles 304 interspersed throughout thecarbon scaffold 300. The porous arrangement of the carbon scaffold 300receives electrolyte dispersed therein for Li ion transport throughinterconnected hierarchical pores 101A and/or the contiguousmicrostructures 107E that, similar to individual carbon-based particles100A and/or 302, define one or more channels including:

-   -   microporous frameworks defined by a dimension 101E of >50 nm        that provide tunable Li ion conduits;    -   mesoporous channels defined by a dimension 102E of about 20 nm        to about 50 nm, generally defined under IUPAC nomenclature and        referred to as mesopores or mesoporous, that act as Li        ion-highways for rapid Li ion transport therein; and    -   microporous textures defined by a dimension 103E of <4 nm for        charge accommodation and/or active material confinement.

The first layer including a first concentration of carbon-basedparticles 100A and/or 302 can be configured to demonstrate an electricalconductivity ranging from 500 S/m to 20,000 S/m. A second, or anysubsequent, layer can be deposited on the first, or any preceding,layer. The second layer can include a second contiguous film formed by asecond concentration of carbon-based particles 100A and/or 302 incontact with each other to yield a second electrical conductivityranging from 0 S/m to 500 S/m, or otherwise lower than the firstelectrical conductivity.

Carbon scaffold 300 may be prepared for subsequent Li infiltration,referred to herein as being pre-lithiated, and later infused with Li ionliquid solution via capillary action to create lithiated carbon scaffold400A as shown in FIG. 4A. Film layers 406A, 408A, 410A, and 412A, eachhaving defined thicknesses in the vertical direction extending from thecurrent collector, may be synthesized in-flight in a microwave reactor,or deposited layer-by-layer in or out of a thermal reactor. Film layers406A, 408A, 410A, and 412A have varying electrical conductivity rangingfrom high, such as at film layer 406A, to low, such as at film layer412A, in a direction orthogonal and away from the current collector,which may also be a sacrificial and/or electrically conductivesubstrate. In an example configuration, each layer of the film layers406A, 408A, 410A, and 412A can be produced with a defined, and aprogressively declining, concentration of carbon-based particles 302 toachieve particular electrical resistance values, such as where:

-   -   The film layer 406A is produced with a relatively high defined        concentration of carbon-based particles 302 conducive for low Li        ion transport and low electrical resistance, at <1,000Ω,        suitable for high electrical conductivity;    -   the film layers 408A and 410A are produced with systematically        decreasing electrical conductivity by engineering the        carbon-based particles 302 to demonstrate desirable interfacial        surface tension to promote wetting of exposed carbon surfaces        with molten Li metal; and    -   the film layer 412A is produced with a relatively low defined        concentration of carbon-based particles 302 conducive for high        Li ion transport and high electrical resistance,        at >1,000-10,000Ω, suitable for high electrical resistance.

Varying electrical conductivity may be at least partially proportionateto interfacial surface tension of a Li ion solution infiltrated into theporous arrangement of the open porous scaffold. Infiltration of the Liion solution (such as including the Li ions 108E) can be performed viacapillary infusion engineered to promote wetting of surfaces of openporous scaffold 102A exposed to Li ion solution. The diffusion pathways109E, as shown in FIG. 1E, ensure that deposition and strippingoperations associated with one or more oxidation-reduction, alsoreferred to as redox, reactions occurring within carbon-based particles100A and/or 302B are uniform. Electroactive material can reside in thepores 105E of the contiguous microstructures 107E when they are used toform the open porous scaffold 102A, which itself may be incorporatedwithin any one or more of the anode and the cathode. In someimplementations, the contiguous microstructures 107E may be formed fromor otherwise contain single-layer graphene (SLG), as shown in FIG. 1C,and/or few-layer graphene (FLG) including from 1 to 10 graphene planes,shown as the agglomerations 101B of multiple layers of the graphenesheets 101C in FIG. 1B. Groupings of the graphene sheets 101C can bepositioned in a substantially aligned orientation along a vertical axisand fused together at substantially orthogonal angles. Anode activematerial or cathode active material may have a specific surface areafrom approximately 500 m²/g to 2,675 m²/g when measured in a driedstate, and may contain a graphene material suitable for lithiation, thegraphene material comprising any one or more of pre-lithiated graphenesheets, pristine graphene, graphene oxide, reduced graphene oxide,graphene fluoride, graphene chloride, graphene bromide, graphene iodide,hydrogenated graphene, nitrogenated graphene, boron-doped graphene,nitrogen doped graphene, chemically functionalized graphene, physicallyor chemically activated or etched versions thereof, conductive polymercoated or grafted versions thereof, and/or combinations thereof.

In any one or more of the discussed examples in relation to lithiatedcarbon scaffold 400A, electrically conductive interconnectedagglomerations of graphene sheets 101B are sintered together to formopen porous scaffold independent of a binder, however alternativeexamples do exist where a binder is used. Configurations with or withouta binder may each involve open porous scaffold 102A acting or serving asan active lithium intercalating structure with a specific capacity ofapproximately 744-1,116 mAh/g, or more. Also, examples include thepreparation of graphene sheets 101B using chemically functionalizedgraphene, involving the surface functionalization thereof, comprisingimparting to open porous scaffold 102A a functional group selected fromquinone, hydroquinone, quaternized aromatic amines, mercaptan,disulfide, sulfonate (—SO₃), transition metal oxide, transition metalsulfide, other like compounds or a combination thereof.

The current collector shown in FIG. 4A, is, for example, at leastpartially foam-based or foam-derived and is can be selected from any oneor more of metal foam, metal web, metal screen, perforated metal,sheet-based 3D structure, metal fiber mat, metal nanowire mat,conductive polymer nanofiber mat, conductive polymer foam, conductivepolymer-coated fiber foam, carbon foam, graphite foam, carbon aerogel,carbon xerogel, graphene foam, graphene oxide foam, reduced grapheneoxide foam, carbon fiber foam, graphite fiber foam, exfoliated graphitefoam, and combinations thereof.

Anode or cathode electrically conductive or insulative material,referred to herein as active material can include any one or more ofnanodiscs, nanoplatelets, nano-fullerenes, carbon nano-onions (CNOs),nano-coating, or nanosheets of an inorganic material selected from:

-   -   bismuth selenide or bismuth telluride,    -   transition metal dichalcogenide or trichalcogenide,    -   sulfide, selenide, or telluride of a transition metal;    -   boron nitride, or    -   a combination thereof, inclusive of molten Li metal interspersed        therein to provide a source for Li ions upon dissociation during        normal electrochemical cell discharge-charge cycles, etc.        The nanodiscs, nanoplatelets, nano-coating, or nano sheets can        have a thickness less than 100 nm. In other examples, the        nanoplatelets can have a thickness less than 10 nm and/or a        length, width, or diameter less than 5 μm.        Producing an Anode or Cathode Created from the Carbon Structures

Example processes for producing a three-dimensional (3D) carbon-basedelectrode, such as that created from lithiated carbon scaffold 400A, caninclude depositing, such as from one or more plasma-based thermalreactors or torches, in which thermal energy is propagated through aplasma and/or feedstock material supplied in a gaseous state,carbon-based particles 100A or 400A to form a first contiguous filmlayer, such as layer 406A shown in FIG. 4A, on a substrate, where thefirst contiguous film layer is characterized by a first electricalconductivity. Each of the carbon-based particles comprises electricallyconductive three-dimensional (3D) aggregates or agglomerations ofgraphene sheets 101B. The aggregates can be orthogonally fused togetherto form open porous scaffold 102A to facilitate electrical conductionalong and across contact points of the graphene sheets.

A porous arrangement formed in open porous scaffold 102A, where theporous arrangement is conducive to receive electrolyte dispersed thereinfor Li ion transport through interconnected pores, such as hierarchicalpores 101A and/or the contiguous microstructures 107E, that define thediffusion pathways 109E. The first contiguous film layer has an averagethickness no greater than approximately 100-200 μm. In an example, abinder material is combined with graphene sheets 101B to retain graphenesheets 101B in a desired position to impart structure to open porousscaffold 102A. The binder may be or comprise a thermosetting resin or apolymerizable monomer, wherein curing the resin or polymerizing thepolymerizable monomer forms a solid resin or polymer with assistance ofheat, radiation, an initiator, a catalyst, or a combination thereof. Thebinder may be initially a polymer, coal tar pitch, petroleum pitch,mesa-phase pitch, or organic precursor material and is later thermallyconverted into a carbon material.

Additional quantities of the carbon-based particles 100A are depositedon the first contiguous film layer to form a second contiguous filmlayer there-upon, the second contiguous film layer having a secondelectrical conductivity lower than the first electrical conductivity andbeing positioned closer to electrolyte 414A and away from the currentcollector, which may be a sacrificial substrate. Li ion solution can beinfiltrated into, such as by capillary infusion action, open porousscaffold 102A to react with exposed carbon on surfaces thereof tofacilitate Li ion dissociation and electric current supply, where theexposed carbon on the open porous scaffold can include a surface areagreater than approximately 100 m²/gm.

Carbon-based particles 100A and/or lithiated carbon scaffold 400A can besynthesized in-flight in a microwave reactor, or deposited in abottom-up manner, referring to a layer-by-layer deposition or growthwithin a thermal reactor, and may then be cast, via a liquid slurry tobe subsequently dried to form a carbon-based electrode that may besuitable for implementation or incorporation within a Li ion battery.Such a slurry may, in some examples, comprise chemical binders andconducting graphite, along with the electrochemically active innatecarbon.

The term hierarchical implies an arrangement of items in which the itemsare represented as being above, below, or at the same level as oneanother. Here, carbon-based particle 100A and/or lithiated carbonscaffold 400A may be grown by layer-by-layer deposition in a thermalreactor to create one or more grades, as indicated by film layers 406Ato 412A of the conductive particles 100A, 302B and/or 402A, referring tothat created by specific control of electrical, referring to contactpoints of graphene sheets 101B, and ionic, referring to the diffusionpathways 109E, conducting gradients throughout the thickness oflithiated carbon scaffold 400A. Tuning of each individually depositedlayer 406A through 412A results in relatively higher electricalconductivity at the current collector interface, and progressive lowerelectrical conductivity moving outwardly therefrom.

The graphene sheets 101B within carbon-based particle 100A can serve asboth electrical conductors, by conducting electric current throughcontact points and/or regions, and as active Li intercalating structuresto provide a source for the specific capacity of the anode electrode at744-1,116 mAh/g, such as 2 to 3 times that otherwise available fromconventional graphite anodes at 372 mAh/g. As a result, interconnected3D bundles of graphene sheets 102 within the carbon-based particle 100Amay be considered as nanoscale electrodes that concurrently enable arelatively high-volume fraction of electrolytically active materialalong with efficient, 3D interpenetrating, ion, and electron pathways.

This unique 3D structure of the carbon-based particle 100A enables bothstorage of electric charge at its exposed surfaces via capacitive chargestorage for desirable high-power delivery, relative to conventionalapplications, and also provides faradaic redox ions within the bulkthereof for desirable high electric energy storage. Redox, as generallyunderstood and as referred to herein, refers to reduction-oxidationreactions in which the oxidation states of atoms are changed involvingthe transfer of electrons between chemical species, most often with onespecies undergoing oxidation while another species undergoes reduction.

Faradaic, as generally understood and as referred to herein, refers to aheterogeneous charge-transfer reaction occurring at the surface of anelectrode, prepared with, and/or otherwise incorporating carbon-basedparticle 100A. For instance, pseudocapacitors store electrical energyfaradaically by electron charge transfer between electrode andelectrolyte. This is accomplished through electrosorption, redoxreactions, and intercalation processes, termed pseudocapacitance.

Roll-to-Roll Processing for Producing an Electrochemical Cell ElectrodeCreated from the Carbon Scaffold

Regarding manufacturing, lithiated carbon scaffold 400A can bemanufactured, to fabricate and/or build electrochemical cell electrodes,such as cathodes and/or anodes, in large-scale quantities by sequential,layer-by-layer, such as layers 406A through 412A shown in FIG. 4A,deposition of concentrations of carbon-based particle 100A and/or 100Eonto a moving substrate, such as a current collector, through aroll-to-roll (R2R) production approach. By consolidating 3D carbonscaffold structures directly out microwave reactors, analogous toexiting plasma spray processes, electrode films can be continuouslyproduced without the need for toxic solvents and binders that areotherwise used in slurry cast processes for battery electrodes.Therefore, battery electrodes employing lithiated carbon scaffold 400Amay be more readily produced with controlled electrical, ionic, andchemical concentration gradients due to the layer-by-layer, sequentialparticle deposition capabilities of a plasma-spray type processes; and,specific elements, such as dopants, can also be introduced at differentstages within the plasma deposition process.

Also, due to the pores 105E and/or the contiguous microstructures 107Einterspersed throughout carbon-based particle 100A, lithiated carbonscaffold 400A may be manufactured in a manner such that it isgravimetrically, referring to a set of methods used in analyticalchemistry for the quantitative determination of an analyte based on itsmass, superior to known devices. That is, carbon-based particle 100A,with pores and/or voids defined throughout 3D bundles of graphene sheets102 and/or conductive carbon particles 104, may be lighter thancomparable battery electrodes without a mesoporous structure includingvarious pores and/or voids, etc.

Carbon-based particle 100A may feature a ratio of active material toinactive material that is superior relative to conventionaltechnologies, in that greater quantities of active material areavailable and prepared for electricity conduction there-through relativeto inactive and/or structural reinforcement material. Such structuralreinforcement material, although involved in defining a generalstructure of carbon-based particle 100A, may not be involved or asinvolved in electrically conductive interconnected agglomerations ofgraphene sheets 101B. Accordingly, due to its high active material toinactive material ratio, carbon-based particle 100A may demonstratesuperior electrical conductivity properties relative to conventionalbatteries, as well as being significantly lighter than such conventionalbatteries given that carbon may be used to replace traditionally usedheavier metals. Therefore, carbon-based particle 100A may be particularwell-suited for demanding end-use application areas that also maybenefit from its relatively light weight, automobiles, light trucks,etc.

Carbon-based particle 100A may be created to rely electricallyconductive interconnected agglomerations of graphene sheets 101B toobtain a percolation threshold, referring to a mathematical concept inpercolation theory that describes the formation of long-rangeconnectivity in random systems. Below the threshold a giant connectedcomponent does not exist, while above it, there exists a giant componentof the order of system size. Accordingly, 3D bundles of grapheneelectrically conductive interconnected agglomerations of graphene sheets101B may conduct electricity from the current collector, as shown inFIG. 4A, toward electrolyte 414A.

Roll-to-Roll (R2R) Plasma Spray Torch Deposition System

As a variation from the presently disclosed atmospheric MW plasmareactor used to produce particle-based output including integrated,contiguous 3D hierarchical carbon scaffold films, a spray torchconfiguration can be employed to produce similar such carbon-basedstructures, such as that shown by roll-to-roll (R2R) system 400V shownin FIG. 4V. Plasma torches permit for materials to be initiallyformulated, similar to waveguided reactor, then accelerated into animpact zone on a substrate surface that can be either moving orstationary. Each zone of the R2R process can provide for unique controlof dissimilar mixed phase or composite material synthesis, formulation,consolidation, and integration, such as densification.

The plasma torch can be used to deposit carbon-based particles on acontinuous, moving substrate to enable an additive type of processcontrol at locations of hot plasma jets depositing the carbon-basedparticles and beyond the plasma afterglow region up to the impact zoneof the substrate. Various properties can be controlled, such as defectdensity, residual stress, through control of deposition thicknesses offilm layers, chemical and thermal gradients, phase transformations, andanisotropy. For electrochemical cell electrode fabrication, not only canthe atmospheric MW plasma torch create formulated and integratedcontinuous 3D graphene films without the need for toxic solvents such asNMP and or use of binders in accordance with conventional slurry castingprocess, but the plasma torch can be used to create integratedelectrode/current collector film structures for enhanced performance ata reduced cost.

FIG. 4V shows a roll-to-roll (R2R) system 400V employing an examplearrangement of a group 444V of plasma spray torches 422V through 428V,such as 422V, 424V, 426V, and/or 428V, all of which are configured toperform layer-by-layer deposition to fabricate, otherwise referred to asgrowing, the carbon-based scaffold 300B, shown in FIG. 3B, and/orvariants thereof, incrementally. Group 444V of plasma spray torches 414Vthrough 420V are oriented in a continuous sequence above the R2Rprocessing apparatus 440V, which, may include wheels and/or rollers 434Vand 436V configured to rotate in the same direction, 430V and 432V,respectively, to result in translated forward motion 436V of sacrificiallayer 402V upon which layers 442V of carbon scaffold 436V may bedeposited in a layer-by-layer manner to achieve a graded electricalconduction gradient proportionate to the concentration level ofcarbon-based particles 100A contained per unit volume area in eachprogressive deposited layer, such as film layers 406V-412V.

Such deposition may involve the positioning of group 444V of plasmaspray torches 414V through 420V as shown in FIG. 4B, with an initial, indirection of forward motion 436V, spray torch 414V extending thefurthest in a downward direction, toward sacrificial layer 404V fromfeedstock supply line 412V, positioned to spray 422V carbon-basedmaterial to deposit initial layer 404V, also may be shown as interimlayer 406A in FIG. 4A, and so on and so forth, of carbon scaffold 300Bon sacrificial layer 402V. Initial layer 404V may be deposited toachieve the highest conductivity values, with each of the subsequentlayers 406V through 410V featuring a proportionately less-densedispersion of carbon-based particle 100A composing carbon-based scaffold300B to achieve a graded electric gradient for layers 422V.

That is, plasma spray torches 414V through 420V may be oriented to haveincrementally decreasing, or otherwise varying, heights as shown in FIG.4V, such that each spray torch from group 444V may be tuned to spray,from spray 422V to 428V, respectively, sprays of carbon-based feedstockmaterial supplied by feedstock supply line 412V. Accordingly, batteryelectrodes can be more readily produced with controlled electrical,ionic, and chemical concentration gradients due to the layer-by-layer,sequential deposition described herein with connection to plasmaspray-torch system 400V, which presents desirable features of plasmaspray type processes; and, specific elements or additional ingredientscan also be introduced at different stages within the plasma-based spraydeposition process described by plasma spray-torch system 400V. Suchcontrol may, extend to tunability of plasma spray-torch system 400V toachieve target electric field and/or electromagnetic field properties ofany one or more of layers 422V.

Group 444V of plasma spray torches 414V through 420V may employplasma-based thermally enhanced carbon spraying techniques to providecarbon coating processes in which melted or heated materials are sprayedonto a surface. The feedstock, coating precursor, is heated byelectrical, plasma or arc. or chemical means, such as a combustionand/or a flame.

Thermal spraying by plasma spray torches 414V through 420V can providethick coatings of approximately a thickness in the range of 20 μm ormore to several mm, depending on the process and feedstock, over a largearea at high deposition rate as compared to other coating processes suchas electroplating, physical and chemical vapor deposition. Coatingmaterials available for thermal spraying include metals, alloys,ceramics, plastics, and composites. They are fed in powder or wire form,heated to a molten or semi-molten state, and accelerated towardssubstrates in the form of μm-size particles. Combustion or electricalarc discharge is usually used as the source of energy for thermalspraying. Resulting coatings are made by the accumulation of numeroussprayed particles. The surface may not heat up significantly, allowingthe coating of flammable substances.

Coating quality is usually assessed by measuring its porosity, oxidecontent, macro and micro-hardness, bond strength and surface roughness.Generally, the coating quality increases with increasing particlevelocities.

Carbon Scaffold Implemented in a Li S Secondary Battery

Group 444B of plasma spray torches 414B through 420B may be configuredor tuned to spray carbon-based material in a controlled manner toachieve specific desired hierarchical and organized structures, such asopen porous scaffold 102A of carbon-based particle 100A and/or 100E withthe contiguous microstructures 107E suitable to be used for Li ioninfiltration via capillary action therein dependant on percentageporosity of carbon-based particle 100A and/or 100D. Total quantities ofS able to be infused into the contiguous microstructures 107E and/ordeposited on exposed surface regions of carbon-based particle 100Aand/or 100D, and other such similar structures. may depend on thepercentage porosity thereof as well, where 3D fractal-shaped structuresproviding larger pores, such as pores 105E, each having dimension 103Ecan efficiently accommodate and micro-confine S for desired timeframesduring electrochemical cell operation. Examples exist permitting for thecombination of S to prevent any resultant polysulfides (PS) migratingout of pores 105E purely by designing and growing structural S, withconfinement of S being targeted at a defined percentage, such as: 0-5%,0-10%, 0-30%, 0-40%, 0-50%, 0-60%, 0-70%, 0-80%, 0-90%, and/or 0-100%,any one or more of such ranges successfully showing of retardation ofpolysulfide migration out of the electrode structure.

Carbon Scaffold Implemented in a Li Air Secondary Battery

Existent Li air cathodes may last only 3-10 cycles, and thus have notyet been universally understood to provide very promising or reliabletechnologies. In such cathodes, air itself acts as the cathode,therefore the reliable and robust supply of air flowing through thecathode, such as through pores, orifices, or other openings, effectivelycurrently precludes realistic applications in consumer grade portableelectronic devices such as smartphones.

Devices can be made with some sort of air pump mechanism, but airpurification remains an issue, given that any amount of impurityprevalent in the air can and will react with available Li in parasiticside-reactions ultimately degrading specific capacity of the overallelectrochemical cell. Moreover, air only provides only about 20.9% O₂,and thus is not as efficient as other alternative current advancedbattery technologies.

Nevertheless, even in view of the above-mentioned challenges, examplesprovided above relating to carbon-based particle 100A, 100D and/or anyvariants thereof implemented in carbon scaffold 300B and/or lithiatedcarbon scaffold 400A can be configured to function in a 3D-printedbattery. Notably, measures can be taken to guard against, such as bytuning to achieve desirable structural reinforcement in certain targetedareas of open porous scaffold 102A, to prevent against unwanted and/orsudden collapse of porous structures, such as to create clogging ofpassageways defined therein. In example, carbon scaffold 300B can bedecorated with a myriad of metal oxides to achieve such reinforcement,which may also control or otherwise positive contribute to mechanicaltunnelling of the structure itself once lithium reacts with air tospontaneously form a solid from that state, etc. Traditionalcircumstances, such as absent special preparations undertaken regardingimplementation of the disclosed carbon-based particle 100A and/or thelike with Li air cathodes can otherwise involve Li ions reacting withcarbon provided in a gaseous state, such that the Li ion and thecarbon-containing gas react to form a solid that expands. And, dependingon where this expansion occurs, can mechanically degrade the overallcarbon-based mesoporous scaffold structure, such as of carbon scaffold300B.

Preparation for Lithiation of Carbon-Based Particles

To enable alternative non-Li or lithiated carbon-based scaffoldedcathodes, such as those confining sulfur, oxygen, and vanadium oxide,over current lithium oxide compound cathodes, as well as to accommodatefirst charge lithium loss, resulting reduced coulombic efficiency, incurrent Li ion cells, a scalable pre-lithiation method for carbon-basedstructured intended for implementation in electrochemical cellelectrodes may be required. As a result, various experimental attemptshave been conducted with carbon-based particle 100A, 100D and/or anyderivative structures based therefrom, including carbon scaffold 300Bsuch as ball milling, post thermal annealing, and electrochemicalreduction from an additional electrode. Such efforts have been used topre-lithiate, such as chemically preparing a carbon-based structure toreact with and/or confine lithium physically and/or chemically, but havemet with uniformity, lithium reactivity, costs, and scalabilitychallenges.

Nevertheless, by fine-tuning reactor process parameters, carbon-basedparticle 100A, 100D, and/or carbon scaffold 300B may be synthesizedand/or fabricated by layer-by-layer deposition process, as substantiallydiscussed earlier, to serve as a carbon-based host structure withengineered surface chemistry, such as including nitrogen and oxygendoping to facilitate rapid decomposition involving disproportionation ofoxides.

Upon thermal activation, which can include the formation of one or moresparks, Li metal can be spontaneously, such as without a pressuregradient and non-reactively infiltrated driven by capillary forces tocreate a controlled, pre-lithiated carbon structure or particle buildingblocks. Subsequently, such pre-lithiated particle building blocks can besynthesized into an integrated composite film with graded electricalconductivity from:

-   -   a high conductivity at a back plane in contact with the current        collector, such as shown by interim layer 406A, to    -   an insulated ion conducting layer at the electrolyte/electrode        plane.        Surface chemistry, as may be related to non-reactive        infiltration of Li metal can be tuned by optimizing oxide        thermal reduction degree, such as an exotherm, by using        thermogravimetric analysis (TGA) or differential scanning        calorimetry DSC analytical techniques.

To address scalability concerns as may be related to transitioning froma low-volume laboratory testing and sample production environment to ahigh-volume large-scale plant capable of fulfilling multiple customerorders simultaneously, the above described pre-lithiation process isreadily adaptable to a continuous roll-to-roll (R2R) format, analogousto other liquid melt wetting processes such as brazing.

Thin film Li clad foil, which can in some configurations includetantalum (Ta) or copper (Cu), can be loaded onto a heated calendaringroll, to be brought into contact with carbon-based particle 100A, orcarbon film, in the case of the spray torch process, in a controlledthermal, dry environment. Thermal residence, such as soak, time,gradient, and applied pressure can adjust and controlled to facilitateboth: (1) activation; and (2) infiltration process steps.

Initiation of Lithiation of the Carbon Scaffold

Prior to the development of Li metal infusion methods into carbon-basedstructures and/or agglomerate particles, efforts have been undertaken toassess the following two scenarios:

-   -   growing microwave graphene sheets that have extended D-spacing        that would allow Li intercalation to occur in-between individual        graphene sheets at a much more efficient or a faster rate than        what would occur in typical, commercially available, graphene        sheets; and, growing FLG in such a way to successfully and        repeatably achieve such higher de-spacing; and    -   using a wet liquid Li metal front that propagates into the        hierarchical pores 101A and/or the contiguous microstructures        107E defined by open porous scaffold 102A of carbon-based        particle 100A and/or 100D, where attraction from Li metal to        exposed carbon-based surfaces to wet the same relative to        otherwise functionalizing exposed carbon-based surfaces.        The presently disclosed thermal reactors can perform post        processing to create highly organized and structured carbons        that have that functioning relating to the infiltration of        molten Li metal and/or other species, such as infiltration of        aluminum into a silicon carbide-sintered material, and hammering        the surface of the particles to promote infiltration of a molten        (Li) metal front without additional pressure from outside        sources. Such efforts permit for continuous wetting instead of        using capillary pressure to push metal into open porous scaffold        102A of carbon-based particle 100A and/or 100D.

FIG. 4A shows a lithiated carbon scaffold formed from severalinterconnected carbon-based particles 402A, similar in form and functionto carbon-based particles 100A and/or 100E, synthesized and deposited atvarying concentration levels in the film layers 406A to 412A, from mostconcentrated to least concentrated. All of the film layers 406A through412A, are configured to be infiltrated, via non-reactive capillaryinfusion methods, with a molten Li metal and/or Li ion solution inliquid state or phase for intercalation of Li ions in-between pairs ofgraphene sheets of the graphene sheets 101B. Example D-spacing ofapproximately 1 Å to 3 Å can be targeted during synthesis of thegraphene sheets 101B to retain more Li ions between alternating graphenesheets than conventional graphene sheet stacks.

Voids 416A, referring to vacant regions or spaces, between adjacentand/or contacting carbon-based particles 402A may be defined by asection of lithiated carbon scaffold 400A positioned away from a currentcollector 420A and facing a liquid-phase electrolyte layer, apassivation layer 418A. Passivation implies a material becoming passive,that is, less affected or corroded by the environment of future use. Inaddition, or in the alternative, a Li ion conduction insulating, orgraded interphase layer can be deposited on layer 412A, such as at thesame location of the passivation layer 418A, facing electrolyte 414A tominimize side reactions with free and/or physically and/or chemicallyunattached Li in ionic form.

Prior to the deposition or placement of any such encasing layer, Li, asprovided by molten Li metal, may be flowed in liquid state into thevoids 416A defined by the carbon-based particles 402A to assist informing electrochemical gradients proportionate to the level ofconcentration of carbon-based particles 402A in each layer of the filmlayers 406A-412A.

Repeated, or cyclical, Li ion electrode, such as the anode or thecathode, usage in secondary batteries can result in problems due tousage of molten Li metal, such as volume expansion during re-depositingin electroplating operations, implying a process that uses an electriccurrent to reduce dissolved metal cations so that they form a thincoherent metal coating on an electrode. The term can also be used forelectrical oxidation of anions on to a solid substrate, as in theformation of silver chloride on silver wire to makesilver/silver-chloride electrodes.

Processes used in electroplating with relation to infiltration of Li ionsolution into lithiated carbon scaffold 400A may be referred to aselectrodeposition, also known as electrophoretic deposition (EPD), andis analogous to a concentration cell acting in reverse.

Electroplating, as described above, with Li ions can result in a volumeexpansion on the order of approximately 400% or more of lithiated carbonscaffold 400A. Such an expansion is undesirable from a stabilitystandpoint micro-mechanically and causes degradation with many deadzones, referring to inactive or non-chemically and/or electricallyactivated regions, therefore ultimately preventing the derivation oflonger lifespans out of so-equipped Li ion batteries. Generally, it isdesirable to have a majority of the Li ion material plate, meaningreduce onto a smooth and uniform surface to therefore facilitate uniformdeposition of Li ions. Removal will also be smooth in a smooth planarinterface.

In practice, Li, when infiltrated into the carbon scaffold 400A may tendto form unwanted dendrites, defined as crystals that develop with atypical multi-branching tree-like form. Such Li ion dendrites, also inthe form of acicular Li ion dendrites, acicular describing a crystalhabit composed of slender, needle-like crystal deposits, grow away fromsurfaces upon which Li ions are infiltrated, such as upon and/orin-between individual graphene sheets 101B. In some circumstances, withenough battery charge-discharge cycling, a dendritic protrusion orprotuberance can grow across all the way through from an anodeincorporating the lithiated carbon based scaffold 400A to a cathodepositioned opposite to the carbon based scaffold within anelectrochemical cell to cause a short route or circuit, describing whenthere is a low resistance connection between two conductors that aresupplying electrical power to a circuit. This may generate an excess ofvoltage streaming and cause excessive flow of current in the powersource. The electricity will flow through a short route and cause ashort circuit.

Capillary Li ion infusion techniques into lithiated carbon scaffold 400Acan address many of the described problems. Nevertheless, a persistentissue encountered in Li ion batteries includes that a conventionalcathode provides only a limited quantity of specific capacity or energycapability. Likewise, on the anode side, decreases have also beenobserved in specific capacity and energy density as well. Thus, even inview of how relatively desirable, in terms of electric energy storagecapacity and current delivery, a Li ion battery may be compared to Limetal hydride or lead-acid, or Ni Cad batteries, even greateradvancements in electric power storage and delivery are possible,regarding the protection against or prevention of unwanted Li-baseddendritic formations, upon the incorporation of any one or more of thepresently disclosed carbon-based materials, such as the lithiatedcarbon-based scaffold 400A, to approach the theoretic capacity of pureLi metal, which has a specific capacity of around 3,800 mAh/g.

Other approaches have been undertaken including the development ofsolid-state batteries, describing no liquid phases at all. However,attention has returned to Li metal, due to oxide electrolyte being usedto achieve and stabilize contact with Li. And, alternatives to Li metalhave also been explored including Si, Sn, and various other alloys.However, even upon elimination of Li metal, a Li ion source may still berequired.

Alternative-to-lithium materials in a Li ion battery electrode structuremay yield the following energy density values: oxides provide 260 mAh/g;and sulfur (S) provides 650 mAh/g. Due to its relatively high energydensity capabilities, it is desirable in battery electrode applicationsto confine sulfur (S), so it is not solubilized or dissolved intosurrounding electrolyte. To that effect, sulfur micro-confinement isneeded, as described earlier in relation to the pores 105E of thecontiguous microstructures 107E of, as shown in FIG. 1E, of the openporous scaffold 102A. A confined (or micro-confined liquid implies aliquid that is subject to geometric constraints on a nanoscopic scale sothat most molecules are close enough to an interface to sense somedifference from standard bulk conditions. Typical examples are liquidsin porous media or liquids in solvation shells.

Confinement, and/or micro-confinement, referring to confinement withinmicroscopic-sized regions regularly prevents crystallization, whichenables liquids to be supercooled below their homogenous nucleationtemperature even if this is impossible in the bulk state. Thus, in viewof the various challenges presented above, and others not discussedhere, various improvements to traditional graphite-based anodes may beachieved by instead employing few layer graphene (FLG) materials and/orstructures, defined as having less than 15 layers of graphene grown,deposited or otherwise organized in a stacked architecture with Li ionsintercalated there-between at defined interval and/or concentrationlevels. Any one or more of carbon-based particle 100A, 100D and/or thelike may be so prepared.

Doing so, going from graphite to FLG, may improve specific capacity fromapproximately 380 to over a 1,000 mAh/g for Li-intercalated carbon-basedstructures. Disclosed materials can replace graphite with FLG to permitfor a higher active surface area and can increase spacing in-betweenindividual graphene layers for infiltration of up to 2 to 3 Li ions, asopposed to just 1 Li ion as commonly may be found elsewhere, as shown byFIG. 1I indicating that the various graphite or graphene layer planescan be controlled, in terms of D-spacing, to achieve various fitments ofLi ions in-between adjacent graphite or graphene layer planes.

In graphene, hexagonal carbon structures in each graphene sheet may staypositioned on top of each other, this is referred to as an A-A packingsequence instead of an A-B packing sequence. An example carbon packingsequence is shown in the chemical structural diagram shown in FIG. 1G,where Li ions can fit in void spaces defined by carbon atoms arrangedand bonded in a hexagonal lattice structure. Particularly,configurations are envisioned for graphene sheets and/or few-layergraphene (FLG) where individual layers of graphene may be stackeddirectly on top of each other to obtain incommensurate, disproportionateand/or otherwise irregular, stacking as shown by Stage 3 in FIG. 1H,which in turn permits for the intercalation of addition Li ionsin-between each graphene layer of FLG structures.

Under traditional conditions and circumstances, the insertion of Li ionsfrom, the top-down or bottom-up in layered graphene structures may proveexceedingly difficult in practice. Comparably, Li ions more easilyinsert in-between individual graphene layers separated by a definabledistance. Thus, the key is to manage and tune exactly how much edge areais available. In that regard, any of the carbon-based structureddisclosed herein are so tunable. And, carbon in graphene is alsoconductive— therefore, this feature provides for dual-roles by: (1)providing structural definition to FLG scaffold electrode structures,such as carbon scaffold 300B and/or lithiated carbon scaffold 400A; (2)and, conductive pathways therein.

Production techniques employed to fabricate any one or more of thecarbon-based structures disclosed herein may indicate a desirability ofadjustment of individual graphene-layer edge lengths relative to planarsurfaces thereof; also, the adjustment of the spacing in betweenindividual graphene stacks may be possible. Graphene, given itstwo-dimensional structure, necessarily provides significantly moresurface area in which Li ions can be inserted. Thus, applying graphenesheets in accordance with various aspects of the subject matterdisclosed herein may provide a natural evolution in the direction ofenhanced energy storage density.

Individual graphene sheets are held in position as a part of the plasmagrowth process. Carbon based gumball-like structures are self-assembledin-flight as described earlier from FLG and/or combinations of to formparticles, such as carbon-based particle 100A, 100D, 402A and/or thelike, with a defined long-range order defined as where solid carbonmaterials demonstrate a crystalline phase structure. Once the positionsof carbon atom and its neighbors are defined, the location of eachcarbon atom can be defined precisely throughout the crystalline phasestructure such that smaller structures agglomerate to form whatresembles a gumball.

Size dimensions of such gumball-like structures, describing individualcarbon-based particles 100A and/or the like, may be on the order of 100nm across at their respective widest points. Larger agglomeratedparticles forming a carbon lattice structure 1800 as shown in FIG. 18can be made up from multiple gumball-like structures may be an order ofmagnitude larger, about 20-30 microns in diameter and provide structuraldefinition to one or more of the film layers 406A-412A shown in FIG. 4A.

In contrast, traditional battery electrode production methods typicallyemploy known deposition techniques such as chemical vapor deposition(CVD) or other fabrication techniques, nanotubes, etc., to growstructures from a defined fixed substrate or surface, and thus do notinvolve the in-flight fusing of carbon-based particles in asubstantially atmospheric vapor flow stream of a carbon-containinggaseous species as disclosed herein. Such known assembly processes andprocedures can tend to be very labor intensive, and they may also permitfor the growth of structures of limited thickness, 200-300 microns inthickness.

Graphene-on-graphene densification of multiple FLG on an originalgumball-based carbon scaffold, such as the carbon-based particles 100A,the carbon scaffold 300B, the lithiated carbon scaffold 400A, and/or thelike may also result in increased energy density and capacity. Suchdensification in target regions of the carbon scaffold may also beperformed or otherwise accomplished after creation of a largeragglomerated particle comprising multiple carbon-based particles 100A.Generally, Li ions may be plated onto electrode prior to reduction,therefore Li ion may transition from an ion to a metal state dependenton battery chemistry. Moreover, in an implementation, similar toelectroplating, graphene may be grown in a stacked manner on othermaterials, such as plastic, and tuned to obtain a desirable brightand/or smooth finish. Such electroplating processes are reversible andmay include separate but interrelated plating process and a strippingprocess, intended to place the Li ions and/or atoms down and for thesubsequent removal thereof.

In continual cyclical use of secondary Li ion batteries, involvingmultiple charge-discharge-recharge cycles, surfaces upon whichcarbon-based structures are grown and/or built may eventually roughenedand therefore susceptible to or accommodative of unwanted dendritegrowth. In contrast, techniques employed to produce carbon-basedparticles 100A and/or the like, as discussed above, substantiallyprevent such dendrites from growing, enabled by the usage of Li metalsubstantially free of impurities along with carbon-based graphenestructures to enable high specific capacity values.

Usage of graphene sheets permits for relatively greater exposed surfacearea available for plating or intercalating operations for theinfiltration referring to non-reactive capillary infusion of Li ions.Thus, any tendency to go to a certain point anymore is removed; and,fundamentally the way plating and stripping occurs may be changed due tothe graphene having a higher surface-area to volume ratio than otherconventional carbon-based materials such as graphite. Li ions may beintroduced at least partially relying upon liquid Li; however, givenLi's predisposition for chemical reactivity with surrounding and/orambient elements, water-based moisture and oxygen must be kept away.Similarly, the introduction of impurities results in deleteriouseffects. Metal-matrix composites have been studied, in relation to thedisclosed carbon-based structures, regarding usage of Li metallicallybonding or otherwise forming a metal-matrix composite with C, thereforeoffering additional options regarding the fine-tunability and managementof reactivity at exposed surfaces.

Li in contact with C may result in circumstances where the free energyof carbide of Li at contact surfaces must be suppressed and/orcontrolled to avoid unwanted reactivity related to spontaneous Liinfiltration in carbon-based particle 100A and/or the like.Traditionally, Li, in a liquid phase, typically forms carbonates andother formations due to the chemistry of the electrolyte. However, whatis proposed by the present examples relates to the creation of arelatively stable solid electrolyte interface (SEI) prior to theintroduction of the liquid electrolyte.

Moreover, multiple methods and/or processes to affect Li ion interfaceareas may be available. For instance, preparing the surface of liquid Liby alloying with Si and other elements will reduce the reactivity andpromote overall Li ion wetting of larger agglomerated particles, eachcomprising multiple carbon-based particles 100A. In an example,approximately less than 1.5% of Li was observed to have preferentiallymoved to exposed surfaces, exposed to the electrolyte.

3D Hierarchical Graphene with Increased Specific Capacity (˜3×) OverConventional Graphite Anodes

Commercial use of graphitic carbon materials for anode active materialsas well as fine carbon black materials for electrical conduction isjustified by their relatively low cost, excellent structural integrityfor the insertion and extraction of Li⁺ ions, safety free from Lidendrite formation, and formation of a protective passivation layeragainst many electrolytes such as that associated with the formation orbuild-up of the solid electrolyte interphase (SEI).

The low specific capacity of graphite at 372 mAh/g, havingstoichiometric formula —LiC₆, however, is a critical limitation and as aresult, can potentially hinder the advance of large-scale energy storagesystems that demand high energy and power densities. By designing andapplying a three-dimensional (3D) graphene with intercalated Li and/or Scompounds electrode approach as disclosed herein by any one or more ofthe aforementioned Figures, a larger loading amount of active anodematerials can be accommodated while facilitating Li ion diffusion.Further, 3D nanocarbon frameworks, such as that defined by open porousscaffold 102A and/or the like) can impart:

-   -   an electrically conducting pathway; and    -   structural buffer to high-capacity non-carbon nanomaterials,        which results in enhanced Li ion storage capacity.        Both (1) and (2) enhance Li ion storage capacity (>1,000 mAh/g)        and enhanced cycling (stability) performance can be achieved        with these 3D structures.        Anode-Electrolyte Interface

The presently disclosed graphene and carbon derivative structures can beincorporated into the anode to enhance performance in demanding Li ionand Li S battery configurations, such as an anode substantially formedof stacked graphene with Li intercalated there-within. Alternatively, orin addition, traditional solid Li metal foil anodes can be used withcarbon-based cathodes featuring the contiguous microstructures 107E(shown in FIG. 1E) in Li S battery system configurations. Nevertheless,issues relating to undesirable chemical side reactions related tosolid-electrolyte interface (SEI) formation can be observed at the Lianode in a Li S cell. In addition to electroplating and electrodissolution of Li in the core redox chemistry of the cell to release Li⁺cations into the electrolyte, a typical construction the anode providesa source of reductant species, while excess Li acts a lightweightcurrent collector and helps combat poor coulombic efficiency. Resultantdegradation of the anode is a significant contributor to reduced cyclelife and limits it application. If the energy density of a Li S cell isset at 400 Wh/kg, the thickness of Li metal is estimated at 1-200 μm,more preferentially 20-50 μm (corresponding to 5-10 mAh/cm). Commercialfoils are 70-130 μm in most cases.

Li is highly reactive and lightweight, making it an ideal candidate forbattery technology designed for high gravimetric energy density.However, this reactivity results in Li reacting with many chemicalspecies it contacts to form one or more unwanted side products. Theseunwanted side reactions (and their corresponding resultant products)typically do not add value and may lead to irreversible loss of Li andother electrolyte components. Consumption of electrolyte or drying ofthe cell and/or loss of Li results in accelerated capacity fade.

SEI Formation

Chemical reactions of Li and electrolyte components form an SEI on thesurface of the Li anode that, in turn, slows reaction of electrolytecomponents with the anode and can reduce degradation and thus improvecycle life. The SEI covers the surface of the anode, and primaryelectrochemical reactions occur through the SEI layer. The nature of theSEI layer affects reaction kinetics and can lower cell voltage due toincreased internal resistance. Despite this, the SEI layer and itsproperties are critical to the performance of the anode and the focus ofmaterials research related to the anode in a Li S cell. While materialsresearch in the electrolyte arena focuses on choosing stable solventsystems or reactive additives that promote a favorable SEI composition,solvents are the main source of organic Li salts in SEI films.

Disordered structure promotes ionic conductivity, while the thickness ofthe SEI layer increases internal resistance. The film stops growing whenelectron transfer is blocked, typically in tens of angstroms. Thecompact stratified layer model is commonly used to describe the SEI on aLi anode. It is considered that the surface film on the anode consistsof a porous interphase and a compact interphase consisting of sublayers.The porous outer layer closest to the solution is nonuniform because thereduction of solution species cannot take place over the entirefilm-solution interface, but rather at defects or holes where electronscan tunnel to the surface. The composition of the SEI changes graduallyupon moving from solution/SEI to SEI/Li. Close to the Li anode surface,lower oxidation states are found, and the SEI can become more compact.

The formation of an SEI offers benefits as well as challenges dependingon the specific chemical and physical properties. For example, a coarseand inhomogeneous SEI such as a disordered mosaic type derived fromsoaking promotes preferential growth through cracks and in regions wherethe SEI is thinner. An intact and smooth SEI where localized defects islargely eliminated effectively suppresses both intrinsic and induced Lidendrite growth, which is desirable for Li ion and Li S batteryconfiguration cell performance. Ideally, an SEI should be chemicallystable, Li ion conductive, compact, uniform, and possess mechanicalrigidity and elasticity to accommodate volume change associated with PSshuttle encountered in typical Li S system cycling.

Anode Morphology

In addition to SEI formation during charge and discharge, Li strippingand plating leads to morphological changes over time. Naturalimperfections in soft Li metal anodes can act as Li dendritic structurenucleation points, the uneven stripping and plating of Li over time canincrease the surface area of the Li anode and correspondingly introduceporosity, such as in the form of defining a plurality of interstitialpore volumes. This phenomenon is referred to as “three-dimensional (3D)mossy growth.” While this process increases the anode reactive surfacearea for electrochemistry, it also promotes continual breaking andreforming of the SEI. This cycling process depletes reactive SEI formingelectrolyte components in the cell over time. And, during cycling,irreversible side reactions can consume Li anode active material anddetract from the Li anode's ability to act as a current collector.

Mossy growth is a 3D omnidirectional moss or bush-like growth. 1D growthforms 3D growth by broadening and branching during filament growth. Suchomnidirectional growth can be explained by a “raisin bread” expansionmodel, where there is no preferred direction and the distance betweeneach raisin increases as the loaf expands. The growth model has nogrowth center, but Li dendrite movement can be restricted due toavailable structural support, where the Li metal anode can act as a baseupon which any growing moss is affixed. Since Li atoms can be insertedover the entire Li anode structure, growth does not necessarily occur atexposed Li anode surface tips but also at distributed growth points orregions. Growth and dissolution of Li mossy structures is a non-lineardynamic process, where Li dendrite structure formation related motionappears random and is not dominated by any direction of the electricfield in the build electrolyte. During dissolution large parts of any Lidendrites formed may become electrically disconnected, which can happeneven if Li dendrites remains attached to its original position at theSEI layer from which they extend, because the electrical contact sitesare substituted by an insulating and passivating SEI layer.

The Li anode surface exposed to the surrounding electrolyte musttypically be relatively smooth to ensure the formation of a uniform SEIlayer. The effect of controlling the starting Li surface roughness candepend on the nature of the native SEI. A simple roll press can be usedto form an artificial SEI with a control surface finish, which canprovide the effect of reducing overpotentials for plating and de-platingin a symmetrical cell.

Barrier Layers on the Anode

An excess of Li can be used to function as a current collector in, forexample, a solid Li metal foil anode in a Li S system to combat lowcoulombic efficiency. In Li ion cells using Li metal, the formation ofLi dendrites (also interchangeably referred to as dendritic structures)has caused safety concerns due to the potential for internal shortcircuit, such as the rapid self-discharge of an affected cell where adendrite extends from the anode to the cathode creating a pathway forelectric or ionic charge to travel rapidly, rather than through theintended path to power a load. The term dendrite covers a range ofstructures including needle-like, snowflake-like, tree-like, bush-like,whisker-like and moss-like structures. In most Li S systems, only mossygrowth is observed in practice and internal short circuits due todendritic growth have not been reported practice issue, however suchpotential issues do present concerns for future demanding useapplications. Accordingly, barrier or cap layer approaches, such aslayers at least partially encapsulating the Li anode to prevent growthof unwanted Li dendritic structures therefrom, have been advanced todeal with Li dendrite growth that has the potential pierce the separatorfor Li ion technology, some of which can be applied to Li S technologiesto combat the shuttle effect and other degradation processes.

Most approaches to dendrite prevention in rechargeable Li cells havefocused on the stability and uniformity of the SEI through use ofelectrolyte additives. Because Li metal is thermodynamically unstable inorganic solvents, such methods are often short lived, as discussedearlier. Despite this, their simplicity for scale up andcommercialization make them attractive.

And alternative approach is to form an ex-situ mechanical barrier on theLi foil anode, the mechanical barrier configured to prevent Li dendritegrowth from Li anode surface exposed to the electrolyte. Examplesinclude polymer coatings or ceramic with a high shear modulus to reducedamage and repair to the protective layer that would otherwise depletereactive components in the electrolyte. Reel-to-reel coating techniquescan be developed for Li coatings; such techniques are used, forexamples, in the semiconductor industry.

Barriers rely on forming a strong mechanical layer while attempting toreduce the impact upon the primary electrochemistry taking place. Theapproach can easily lead to high internal resistance within the cell ifthe barrier layer blocks electrochemical activity. Polymer layers can becast onto Li and dried; the advantages are that flexibility of thepolymer makes them robust to volume changes during cycling. The issue isto find a conductive polymer or to achieve a thin coating that does notsignificantly increase internal resistance in the cell. Polymer layersare required to be insoluble in the electrolyte and stable in thepresence of polysulfides, nucleophiles, and radicals.

SEI formed from organic solvents is typically brittle and thereforecannot withstand mechanical deformation, leading to the formation ofcracks. Cracks enhance Li ion flux and result in dendrite formation andnew SEI formation. The recurring breakage and repair of the SEI consumesLi and electrolyte causing battery failure. Volume change is the mainissue that defeats most approaches to forming a stable SEI. A smart SEIlayer has been developed with elasticity using an in-situ reactionbetween Li and Polyacrylic Acid (Li PAA). Li PAA has good uniformbinding properties and is flexible enough to accommodate Li deformation.

Mechanically Strengthened Hybrid Artificial Solid-Electrolyte Interface(A-SEI) Cap Layer for Li-ion and Li S Anodes

Differentiating from tried and partially successful approaches regardingefforts at developing an effective barrier or cap layer geared towardsrestricting Li dendrite growth from the Li anode, a solution is proposedthat combines any one or more of the carbon-containing aggregates, suchas the self-nucleated graphene platelets discussed in connections withany one or more of the Figures, with available polymers to generate abarrier layer. Disclosed carbons can act as a type of mechanicalstrength enhancer for a solid Li metal foil anode or a carbon-basedanode with Li intercalated therein to effectively suppress lithiumdendrite formation on exposed metallic lithium on the anode and enablestable, long-lifetime Li—S batteries. Such efforts may be independent ofor used in conjunction with any one or more traditional Li dendritegrowth mitigation techniques, including:

-   -   usage of electrolytes or additives in electrolytes that can help        develop stable and uniform SEI layer on the Li anode internally;    -   application of an artificial SEI (A-SEI) layer on the Li anode        externally prior to battery assembly; and    -   preparation of a carbon and Li composite material by infusing Li        into the 3D structural material of a given carbon-based        scaffolded structure.

Presently disclosed techniques seek to combine multiple activecomponents and a mechanical strength enhancer, such as a polymercombined with the disclosed carbons, to fabricate an A-SEI thin film tocreate an ultra-stable Li anode suitable for implementation in Li—Sbattery systems. The proposed A-SEI is ideal in many respects andprovides at least the following features:

-   -   chemical and electrochemical stability in the presence, such as        contact, of Li metal, electrolytes and other battery components        at typical Li ion or Li S operational conditions, such as        temperature, pressure, current and voltage range;    -   mechanical strength configured to suppress Li dendrite formation        from the Li anode;    -   flexibility or elasticity to accommodate volume change        attributable to polysulfide (PS) shuttle encountered during        charge-discharge operational cycling in Li S battery systems;    -   conformality and uniformity by substantially surrounding and        adhering any and all surfaces of the anode, such as a solid Li        metal foil anode or a carbon-based anode with Li intercalated        therein, exposed to surrounding electrolyte; and    -   high ionic conductivity for desirable Li⁺ ionic transport        throughout the cell yielding enhanced power deliver and cell        longevity.

Alternative, or in addition, to incorporation of polymer into carbons,inorganic chemicals can be added to the proposed barrier layer. Suchinorganic chemicals can include any one or more of but not limited to:aluminum oxide (Al₂O₃), lithium fluoride (LiF), polysulfides such as(Li₂S₆), phosphorus pentasulfide (P₂S₅), lithium phosphate (Li₃PO₄),lithium nitride (Li₃N), silicon dioxide (SiO₂), molybdenum disulfide(MoS₂), Li₂S₃, any one or more of which can provide a suitable materialto form a passivation layer (such as a material becoming “passive,” thatis, less affected or corroded by the environment of future use) due torelatively high chemical stability. However, these inorganic chemicalscould, for example, also potentially hinder desirable and necessary Liion (Lit) transport from the anode to the cathode, should a barrierlayer produced incorporating at least some of these inorganic chemicalsbe excessively thick. Polymers can be added to mixtures including theseinorganic chemicals and collectively added to any one or more of thepresently disclosed carbon derivatives to form the barrier layer. Suchpolymers can include cross-linked variants of polydimethylsiloxane(PDMS), polystyrene (PS), bis (1-(methacryloyloxy)ethyl)phosphate,2-Hydroxyethyl Methacrylate-based adhesion promoters including any oneor more of succinate, maleate phthalate, or phosphate, glyceroldimethacrylate maleate, polyethylene glycol (PEO), poly (3,4-ethylenedioxythiophene)(PEDOT), styrene-butadiene rubber (SBR), poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP), polyvinylidenefluoride (PVDF), or polyvinylidene difluoride (PVDF). Such polymers areelastic and self-healing, and therefore can accommodate substantialvolume change during battery cycling. However, their lack of rigiditymay not be sufficient to suppress dendrite formation over extended usagedurations.

To best combine beneficial characteristics of both inorganic and/orpolymer-based A-SEI while concurrently further enhancing the mechanicalstrength and/or integrity of a barrier layer prepared as a thin film, ahybrid A-SEI is disclosed. The hybrid A-SEI layer can be prepared toinclude any one or more of:

-   -   active inorganic components, such as any of those presented        earlier and/or including LiF, LiN₃, Li-metal alloy, Li—Si,        Li₃PO₄, LiI, Li₃PS₄, higher cross-linkable analogs of Zn, Sn,        Sr, Ln, Al, or Mo, and/or the like; and    -   polymer-based and mechanical enhancers, including any one or        more of the disclosed carbon-based structures with polymer        binders (such as SBR) incorporated there-within to provide a        structural reinforcing and flexure material; etc.

Suitable fabrication technique employed to produce the hybrid A-SEIlayer can include any one or more of drop casting, doctor blade coating,spray coating, UV curing, thermal curing, etc.

FIG. 4B shows a schematic of a simplified schematic diagram of an A-SEIprotected anode 4B00, which can be an example of the carbon-basedelectrode structure shown in FIG. 3 . In some other implementations, andunlike the electrode shown in FIG. 3 , the electrode shown here in FIG.4B can be prepared to not be carbon-inclusive and as a solid Li metalfoil anode 4B12 supported by a copper foil current collector 4B14. Thesolid Li metal foil anode 4B12 has an example hybrid artificialsolid-electrolyte interphase (A-SEI) layer deposited there-upon, thehybrid A-SEI composed here of two active component layers, a firstactive component layer 4B04 deposited on a second active component layer4B06, both of which substantially encapsulate the solid Li metal foilanode 4B12, according to some implementations. Either of the activecomponent layers can include or be formed of any combination of thepresented active components (or others), as well as polymer-based andmechanical enhancers. The first active component layer 4B04 canprimarily serve as a physical barrier or cap layer and prevent directcontact between Li metal contained within the solid Li metal foil anode4B12 and an electrolyte 4B02 surrounding the solid Li metal foil anode4B12. Such a confirmation of the first active component layer 4B04prepared as a barrier layer can prevent unstable SEI formation,electrolyte decomposition and desiccation, which can be beneficial tomaintain high efficiency during the lifetime of Li—S battery and enablea relatively low electrolyte-to-sulfur (E/S) ratio (such asapproximately 4.2 μL/mg).

Complementing the preparation of the first active component layer 4B04as a physical barrier or cap layer, the second active component layer4B06 can be prepared to primarily enable uniform Li deposition on thesurface of the solid Li metal foil anode 4B12 exposed to the electrolyte4B02, such as through orifices and/or void regions formed in any one ormore of the first and second active component layers 4B04 and 4B06,respectively, to correspondingly suppress formation of Li dendrites thatextend from solid Li metal foil anode 4B12. A mechanical strengthenhancer including any one or more of the disclosed carbon-basedaggregates, such as multiple graphene platelets substantiallyorthogonally fused together, can include a first configuration 4B08, andoptionally, a second configuration 4B10 translated in position relativeto the first configuration 4B08. The mechanical strength enhancer,including and referring to both the first and second configurations 4B08and 4B10, respectively, can be configured to at least partially assistin retaining the A-SEI in a desired location, position, or configurationnecessary to result in an extended battery lifespan. Moreover, the firstand second configurations 4B08 and 4B10 can be prepared to increase thestrength of the A-SEI altogether (such as both the first component layer4B04 and the second component layer 4B06), as reflected in a Young'smodulus (>6 GPa) of the hybrid A-SEI that therefore prevents Li dendritegrowth.

FIG. 4C shows the example shown in FIG. 4B prepared with an anode formedof the multi-layered carbon-based scaffolded structure shown in FIG. 3 ,according to some implementations. Like reference numerals in FIG. 4Brefer to like components in FIG. 4B, with the exception that the solidLi metal foil anode 4B12 is replaced with the porous carbon-basedscaffolded structure first shown and described in FIGS. 3 and 4A, whichmay be infiltrated with Li to provide many of the anode-likecapabilities or characteristics of the solid Li metal foil anode 4B12regarding provision of Li ions (Li⁺) suitable for ionic transportrelated to electrochemical migration required for proper Li ion and/orLi S cell cyclical operation. Given that Li prevalent within thecarbon-based scaffolded structure shown in FIG. 4C can theoreticallyalso form dendritic structures, any one or more of the disclosedcomponents related to the hybrid A-SEI can be re-configured tosubstantially encapsulate and protect such a carbon-based anode fromexperiencing Li dendritic growth as well.

FIG. 4D shows a table 4D00 of various example conventional chemicalbinding materials or substances, also referred to as “binders,” any oneor more of which can be used to bond and/or bind together portions ofcarbon-containing materials included in the hybrid A-SEI layer shown inFIG. 4B and FIG. 4C to enhance Li dendrite formation protection,according to some implementations. Requirements for binder systems andmechanical strength additives to fabricate mechanically strengthenedhybrid artificial SEI, and proposed solutions are discussed herein.

Substantial encapsulation of Li anode surface with a thin, uniform andmechanically robust A-SEI layer, which prevents direct contact betweenLi metal and bulk electrolyte while enabling fast Li⁺ transport, uniformLi deposit and suppressing dendrites formation, requires a carefullydesigned formulation including the following characteristics:

-   -   desirable chemical resistance to the electrolyte;    -   desirable Li wetting and adhesion;    -   minimal shrinkage during drying or curing;    -   high packing density of mechanical strength enhancer in the        A-SEI layer; and    -   high Li⁺ permeability of the encapsulation layer.

An A-SEI layer formed with a flexible polymeric matrix, providing goodadhesion to Li surfaces that is filled with active components listedabove and having a relatively high Young's modulus additive isdesirable. Styrene-Butadiene Rubber (SBR) linear polymer is an exampleof a well-known flexible polymeric binder that can be used.

As has been demonstrated experimentally, SBR-based hybrid layer coatingssignificantly improve Li—S full cells cycling compared to cell with anuntreated Li anode. However, when such a linear polymer is being used asa binder of the protective A-SEI layer, it's prolonged exposure toelectrolyte may result into dissolution of the polymer over time, andcorresponding protective layer degradation.

A stability of a protective A-SEI layer coated onto the anode can beimproved by increasing adhesion of the A-SEI layer to an Li surfaceexposed to the electrolyte via incorporation of one or more functionalgroups such as —OH, —COOH, —NH₂ or others into a flexible polymericstructure to provide for and facilitate ionic bonding to metal surfaces.For example, dicarboxyl-terminated polybutadiene and its co-polymers canbe used, including poly(ethylene-co-acrylic acid) copolymer, which cancombine flexible polyethylene units with PAA units with strong affinityto Li and is another good example of an improved linear polymericbinder.

Optimal solutions to achieve a good chemical resistance to theelectrolyte can include a formation of cross-linked polymeric networkwhere polymer chains are interconnected into 3D-network preventing themfrom dissolution over time. Variation of cross-linking density andmonomeric and/or oligomeric blends compositions will also allow for thetuning of A-SEI coating layer flexibility, good Li wetting and adhesion,and chemical resistance to electrolyte. Various types of curing,including UV or thermal curing, can be performed on any one or more ofvinyl, acrylate, methacrylate groups. In addition, or alternative,epoxy-based curing can be used for cross-linked polymeric networkformation.

For example, the following mono- and di-functional acrylate andmethacrylate monomers and their combinations can be used to form UV- orthermally curable cross-linked polymeric network:

-   -   polybutadiene diacrylate, which can be used to impart improved        flexibility to a polymeric blend;    -   trimethylolpropane triacrylate, which can be used to impart        cross-linking density control to a polymeric blend; and    -   bis[2-(methacryloyloxy)ethyl] phosphate and its mono-functional        analog, which can be used to impart improved adhesion and        lithium binding capability to a polymeric blend.

Such acrylate/methacrylate monomer-based blends with initially lowviscosity can eliminate a need for solvent addition into a protectiveA-SEI layer composition and allow to form A-SEI coating with optimalflexibility, Li wetting and adhesion, chemical resistance to electrolyteand Li⁺ permeability.

A symbiotic approach can also be implemented, such as involving linearpolymer chains with desirable functionality such as flexibility as maybe provided by SBR, PBD, etc., and adhesion (PAA, etc.), as well aslithium binding capability (PEO, etc.) are blended with monomer/s and asolvent. While a use of linear polymer chains alone as binders mayresult into their dissolution over time, entrapment of such linearpolymer chains in a cross-linked network can prevent such dissolution.Moreover, long polymer chains can concurrently minimize film shrinkageafter curing. Similar concepts as described above can be extended toepoxy-based systems curable under ambient conditions in contrast to(meth)acrylate systems, which may require an inert environment to formcross-linked network.

FIG. 4E shows an example 4E00 of the formation of zinc acrylate, amechanical strength enhancing additive for the A-SEI shown in FIG. 4Band FIG. 4C, according to some implementations. Another important aspectof formation of the A-SEI as described earlier, is to form it as adefect-free (such as without pinholes or cracks) thin film having a highmechanical strength and providing good dispersibility of fillermaterials potentially used in its formation, as well as a high carbonparticle packing density within the A-SEI. Both preferences can be byusage of nanofillers. Nanosized materials, such as nanofillers, having ahigh Young's modulus can be the most beneficial to be employed asmechanical strength enhancers in a final A-SEI film.

For example, when ultra-thin (<2 μm) coatings are needed, the morphologyof nanofiller particles can become critical. Mechanical strengthenhancers having a substantially 2D-morphology (such as graphene,nano-clay, Mica) composed of nano-platelets aligning under applied shearcan be more beneficial in terms of imparting mechanical strength orother beneficial properties, such as dispersibility of fillers, to theA-SEI in comparison to 3D nanofillers having a more spherical particlegeometry.

Graphene, such as when organized as multiple graphene platelets fusedtogether at substantially orthogonal angles, can provide optimalmechanical strength enhancement due to its extremely high Young'smodulus. Therefore, such a high Young's modulus graphene material can beused as strength enhancing additive in A-SEI fabrication. Uniquegraphene materials having a substantially folded or wrinkled morphologymay be especially beneficial for such application due to specifics ofthe structure combining highly crystalline and rigid graphene sp²-boundcarbon domains with softer and more flexible “wrinkle” areas. Such acombination will allow graphene structures to accommodate for volumetricshrinkage of the A-SEI protective layer in fabrication and whileexperiencing cross-linking of formative polymers.

Graphene allotropes can be functionalized with epoxy, amine, thiol,carboxylic acid, (meth)acrylate, vinyl and —Si—H groups, any one or moreof which can be incorporated into a blend to further enhance filmintegrity. Such functionalized graphenes can be covalently bound intothe matrix and cured either via epoxy groups cross-linking, free-radicalinitiated cross-linking of vinyl or (meth)acrylate groups orcross-linking of —Si—H groups with di-functional molecules containingdouble bonds on either end, or combination of such curing methods.

Of note, the same material may provide multiple functions, such as anyone or more of:

-   -   encapsulation of the Li surface, such as to serve as a physical        barrier to prevent direct contact between Li metal and        electrolyte;    -   enabling uniform Li deposition; and    -   suppression of dendrite formation by acting as a mechanical        strength enhancer of the A-SEI.

Examples of such materials are curable organic salts of Zn, Sn, In andother metals. For example, Zn acrylate deposited on a Li surface andcross-linked via UV- or thermally, can create a Zn polyacrylate layer,often referred to as “dental cement,” due to its high compressivestrength and good chemical resistance at pH>4.5. Such a cured film canprovide mechanical robustness, while Zn²⁺ ions will exchange with Li⁺ions to enable their transport through the film.

FIG. 4F shows an example formation pathway 4F00 for a metal polyacrylateuseful to protect a Li electrode (such as an anode), according to someimplementations. This example metal polyacrylate can be incorporated inany one or more of the example A-SEI formulations discussed earlier, forany one or more of the discussed benefits, such as strengthening, etc.,to provide, for example, a self-standing, UV-cured semi-interpenetratingpolymer network

EXAMPLES

FIG. 4G shows a pair of photographs, 4G00 and 4G02, respectively, of anexample SnF₂/SBR coating on a control Hohsen Li anode with a Cu foilcurrent collector (referred to as a “Hohsen Li/Cu foil”), according tosome implementations. The thin film was fabricated by a doctor bladetechnique on Hohsen Li/Cu foil and baked at 60° C. to accelerateassociated chemical reactions and drying processes. A yield of 0.3 mgand 2.3 μm SnF₂/SBR coating was achieved. The photograph 4G00 shows theSnF₂/SBR coating on the Hohsen Li/Cu foil after doctor blade coating;and the photograph 4G02 shows the SnF₂/SBR coating on the Hohsen Li/Cufoil after baking at 60° C. for 20 hrs.

FIG. 4H shows a graph 4H00 of the specific discharge capacity (in mAh/g)of example Li—S full cells with a LiF/Li—Sn alloy hybrid A-SEI treatedLi anode and an intact Hohsen Li control foil with a cathode, accordingto some implementations. A noticeable improvement in performance of theSNF₂/SBR-Li hybrid A-SEI combination for the Li—S full cells withLiF/Li—Sn alloys is shown over a conventional Hohsen Li control.

FIG. 4I shows a photograph 4I00 of an example Si₃N₄/SBR A-SEI coating onthe control Hohsen Li/Cu foil, according to some implementations. A thinfilm was fabricated by a doctor blade on a Hohsen Li/Cu foil and bakedat 60° C. to accelerate related chemical reaction and drying processes.A yield of 0.3 mg and 1.6 μm Si₃N₄/SBR coating was achieved.

FIG. 4J shows a graph 4J00 of the specific discharge capacity (in mAh/g)of example Li—S full cells prepared with a LiN₃/Li—Si hybrid A-SEItreated Li anode and an intact Hohsen Li control, according to someimplementations. The A-SEI covered Li anode (referred to as at leastSi₃N₄—Li) was tested in Li—S full cells and showed significantlyincreased stability in early cycles.

FIG. 4K shows a photograph 4K00 of an example graphite fluoride/SBRA-SEI coating in a control Hohsen Li/Cu foil anode, according to someimplementations. LiF and graphite were combined to form an A-SEI withSBR polymer binder. The thin film was fabricated by a doctor blade onHohsen Li/Cu foil and baked at 60° C. to accelerate the reaction anddrying process. Lower than 0.1 mg and about 1.3 μm graphite fluoride(GF)/SBR coating yield was achieved.

FIG. 4L shows a graph of the specific discharge capacity (in mAh/g) ofan example Li—S full cell prepared with a LiF/graphite hybrid A-SEItreated Li anode and an intact Hohsen Li control with cathode, accordingto some implementations. The ASEI covered anode (graphene-F, shown asGF-Li) was tested in Li—S full cell and showed significantly increasedstability in early cycles.

Protective Carbon Interface Layer for Lithium Metal Anode Protection

Alternative or additive configurations to the discussed A-SEI exist toaddress the various current limitations in Li-ion and Li S batteries.Notable challenges can be attributed to volumetric expansion observed inthe cathode, as well as parasitic reactions observed in a traditional(such as unprotected) solid Li metal foil anode. Example undesirableparasitic reactions sought to be prevented can include at leastfollowing:

-   -   overabundant formation of the SEI, which can lead to electrolyte        consumption;    -   Li dendritic formation resulting from uneven current        distribution leading to internal shorting and inactive or “dead”        Li;    -   corrosion of the lithium metal surface resulting from reactants        (i.e., polysulfides dissolution) into the electrolyte; and    -   suppressing or eliminating parasitic reactions associated with a        solid foil Li metal anode can enable safe, cost-effective, and        higher energy density batteries useful across many end-use        application areas.

Conventional battery producers have run into challenges related toparasitic side reactions observed in traditional with Li metal anodes,contributing to potential undesirable Li dendrite growth. Attempts ataddressing such parasitic side reactions can include, for example:

-   -   replacement of the liquid electrolyte in a system for a solid        electrolyte composed of different polymers, ceramics, or        polymers and/or ceramics such as lithium phosphorous oxynitride,        which tend to include high ionic conductivity materials such as        fluoride/sulfide in some combination;    -   introduction of a protective barrier or cap layer directly on        the Li metal made up of polymers and ceramics to protect the        lithium metal itself from the liquid electrolyte, such        protective layers include LiF, LiO, Li₂S, and other common        lithium alloying or conducting materials;    -   create a patterned layer on-top of the solid Li metal foil anode        to redistribute electrochemical current across the electrode;    -   add metal Li alloying additives such a titanium (Ti), tin (Sn),        or silicon (Si) have been used to help reduce parasitic        reactions; and    -   add a mechanically robust layer that prevents the growth of        dendrites outwards to the current collector.

FIG. 4M is an example schematic diagram of a protected electrode (anode)4M00 of a carbon-containing layer (such as an electrically insulatingflaky carbon layer 4M04) including carbon allotropes. The electricallyinsulating flaky carbon layer 4M04 can, in some examples, be depositedon, around, or substantially encapsulate a naturally occurringsolid-electrolyte interface (SEI) to prevent unstable formation of thenaturally occurring SEI. Carbon allotropes particle sizes can beincorporated within the electrically insulating flaky carbon layer 4M04,shown as laminated on top of a lithium-clad current collector foil 4M06,which supports a traditional solid Li metal foil anode 4M10.Alternatively, in some configurations, the lithium-clad currentcollector foil 4M06 may be configured as a functional anode. Stillfurther, the electrically insulating flaky carbon layer 4M04 can be,alternatively, laminated onto a carbon-based anode including graphitescaffolds or sheets of few layer graphene with Li intercalated therein.Any one or more of these described configurations are suitable for usagein a Li ion or a Li S battery. The electrically insulating flaky carbonlayer 4M04 can have a thickness approximately between 0.1 μm and 50 μmand include one or more carbon allotropes (such as two distinctallotropes) or functionalized carbons (such as graphene oxide, andcarbon nano onions, which can a define various interstitial pore volumesinterspersed throughout the electrically insulating flaky carbon layer4M04 permitting for Li⁺ ion transport there-through via pathways 4M14,and through an electrolyte 4M08, as may be necessary for proper cellfunctioning) with or without doping or functionalization. The carbonallotrope particle sizes can range from 0.01-10 um. The addition of theelectrically insulating flaky carbon layer 4M04 acts as a “carbonsheath” to protect the Li metal contained in the solid Li metal foilanode 4M10 (which, in some configurations, can alternatively be acarbon-scaffold anode including multiple graphene sheets with Liintercalated there-between) from interactions with the electrolyte. Theelectrically insulating flaky carbon layer 4M04 does so by providing adesirable surface for a SEI (or, alternatively, a A-SEI such as thatdiscussed earlier) to grow on, impedes polysulfide (PS) from reachingthe lithium metal anode, improves the uniformity of Li-ion flux duringnormal battery operational charge-discharge cycling, and adds mechanicalbenefits geared to prevent Li dendritic growth extending from the anodetowards the cathode, as well as assisting regulation of volumetricexpansion and contraction.

To suppress Li dendrite growth from the solid Li metal foil anode 4M10during battery operational cycling, the electrically insulating flakycarbon layer 4M04 can be formed as a layer of uniform film having aYoung's modulus of approximately >6 GPa. Graphene oxide, a materialhaving Young's modulus of 380-470 GPa, is an example of a suitablecarbon-based candidate to achieve appropriate Li dendrite suppression.Compared to the electrically conductive graphene, graphene oxide iselectrically insulating, and prevents Li dendrite deposition on top ofthe electrically insulating flaky carbon layer 4M04. Any Li presentwould be deposited underneath the electrically insulating flaky carbonlayer 4M04 instead, due to its blocking and insulative properties, someLi⁺ ions 4M12 would rather adhere to the underside of the electricallyinsulating flaky carbon layer 4M04 rather than forming long dendriticstructures extending towards the cathode. Graphene oxide flakes canoverlap with each other to form the electrically insulating flaky carbonlayer 4M04 as a conformal film. This conformal graphene oxide film,however, can induce high impedance. Therefore, the addition of acollection of carbon nano onions 4M12 can produce gaps within thegraphene oxide stack (and thus the electrically insulating flaky carbonlayer 4M04) as a whole, which reduces impedance due to enhanced Litransport (through, for example, one or more pathways 4M14 toward acathode 4M02) and allows for better release of the film from the PETsubstrate.

Carbon nano onions, having (for example) a relatively high surface areaof approximately 10 m²/g-90 m²/g, more preferentially approximately 30m²/g, would help with polysulfide (PS) adsorption, preventing the PSanions from reaching the Li metal anode surface and undergoing chemicalreduction to form Li₂S(S) that would lead to irreversible sulfur andlithium capacity lost.

The electrically insulating flaky carbon layer 4M04 can be prepared in asubstantially binder-free manner. When compared to films consisting ofindividual particles held together with binders, the two-dimensionalshape of graphene oxide creates a more efficient packing betweenindividual graphene oxide sheets, forming a denser film strongly heldtogether by a high degree of interlayer π-π bonds. Moreover, thesheet-like stacking of graphene oxide inhibits crack growth due to thecomplex, high surface area pathways required for crack propagation inthe direction perpendicular to the graphene oxides sheets, improving theintegrity of the film. Additionally, conventional binders would fill thevoids between the carbon particles, creating high impedance forlithium-ion transport. Additionally, graphene oxide can react with Limetal and form LiOH at the interphase as a stable SEI. Since grapheneoxide is insulating, it would not interact with the electrolyte to formSEI on the carbon surface.

The electrically insulating flaky carbon layer 4M04 can optionallyinclude multiple types of carbon with variable porosity, surface area,surface functionalization, and electronic conductivity to influence thereactivity of carbon with contaminants from the surrounding environment(external to the solid Li metal foil anode 4M10), such as components ofelectrolyte in a Li cell such as PS, and the layer can include bindersor other additives to supplement the carbon sheath to produce a sheathwith variable density, porosity, carbon fraction, reactivity, electronicconductivity, and can easily conduct lithium ions or lithium containingmolecules to facilitate the lithium shuttling between cathode and anode.An optimal usage of the disclosed carbons here is to capture unwantedcontaminants prevalent in the electrolyte and prevent them from reactingwith the Li surface, instead reacting with the surface of theelectrically insulating flaky carbon layer 4M04. The electricallyinsulating flaky carbon layer 4M04 must have excellent cohesion to theLi as determined by the fabrication method and composition of the layer(which is mostly comprised of carbon).

FIG. 4N is an example schematic diagram of a roll-to-roll apparatus 4N00prepared for fabrication of a carbon-on-lithium anode, such as theprotected electrode 4M00 of FIG. 4M showing the electrically insulatingflaky carbon layer 4M04 deposited on the solid Li metal foil anode 4M10.The roll-to-roll apparatus 4N00 can be configured to utilize any methodof compression to transfer a carbon containing coating (used to generateor provide the electrically insulating flaky carbon layer 4M04) onto thesurface of Li (such as a surface of the solid Li metal foil anode 4M10that would be exposed to the electrolyte 4M08 upon completion offabrication, etc.) from another substrate, such as roll-to-rolllamination and release.

The fabrication of the carbon-on-lithium anode can utilize any method ofcompression to transfer the carbon containing coating, denoted in FIG.4N by a carbon interface 4N06 cast onto a release film 4N04, which maybe a Polyethylene Terephthalate (PET) release film, onto the surface ofLi from another substrate by using any known techniques, such asroll-to-roll lamination and release. For example, the electricallyinsulating flaky carbon layer 4M04 can be prepared including grapheneoxide and carbon nano-onions by being first mixed to form a slurry,which is then cast onto PET release film, such as the release film 4N04,and dried at 60° C. under vacuum. After drying, the film is thentransferred via roll-lamination (such as by rotation of a first andsecond roll 4N02 and 4N12, respectively) onto a lithium-clad copper foilformed from compression of a Li layer 4N08 onto a copper foil 4N10, in adry-room environment.

The application of pressure to transfer the carbon interface 4N06 fromthe release film 4N04 to the Li layer 4N08 can be achieved by, forexample, calendaring the carbon interface 4N06 (such as when prepared asa protective carbon layer) onto the Li layer 4N08 and then releasing therelease film 4N04. Upon doing so, the carbon interface 4N06 will adherefirmly to the Li layer 4N08 due to the intrinsic adhesive property of Limetal. The adhesive Li metal would therefore assist releasing the carboninterface 4N06 off from the release film 4N04, completing fabrication ofthe protected electrode 4M00 shown in FIG. 4 .

Aside from the configurations of the protected electrode 4M00 shown inFIG. 4M produced by the roll-to-roll apparatus 4N00, several alternativeconfigurations are possible. For example, CNOs can be replaced, or addedto, with the inclusion of one or more other several carbon allotropes,each presenting distinct chemical and mechanical properties.Nanodiamonds (also known as “diamond nanoparticles,”) can includediamonds having a size below 1 micrometer) can be dispersed throughoutand therefore reinforce the electrically insulating flaky carbon layer4M04 and enhance various properties, including mechanical robustness,electrical insulation capabilities, be non-SEI forming and protectagainst the incursion of polysulfide (PS) species into the solid Limetal foil anode 4M10 (or carbon-based anode containing Li). Othercarbon-based substances that can be dispersed in addition or alternativeto nanodiamonds throughout the electrically insulating flaky carbonlayer 4M04 can include:

carbons such as SP² hybridized carbons, reduced graphene oxide (rGO),and/or various forms or types of graphene can lead to improved stackingand layer formation of one or more layers of the electrically insulatingflaky carbon layer 4M04. exfoliated and oxidized carbons configured tobe incorporated within the electrically insulating flaky carbon layer4M04 to impart a more uniform layered structure thereto; solvents suchas tetrabutylammonium hydroxide (TBA) and dimethyl formamide (DMF)solvent treatments can be applied to the exfoliated and oxidized carbonsincorporated within the electrically insulating flaky carbon layer 4M04to impart better wetting of the carbon to achieve better carbondispersion uniformity throughout the electrically insulating flakycarbon layer 4M04;

-   -   graphene fluoride added to carbon slurry including any one or        more of the presently disclosed 3D hierarchical carbon        structures or agglomerations to enhance SEI formation reactions        between the carbons and Li metal exposed thereto, all while        without disturbing the layered structure of protected electrode        4M00;    -   addition of dopants to the crystalline structure of carbons        incorporated into the electrically insulating flaky carbon layer        4M04; one or more functional groups can also be added to the one        or more doped carbons within a carbon-based scaffold or matrix        incorporated into the electrically insulating flaky carbon layer        4M04;    -   addition of functionalized carbons into the electrically        insulating flaky carbon layer 4M04, especially the ones with F,        Si groups can be included or deposited beneath the layered        carbon barrier to form stable SEI on Li and carbon interphase;        and    -   addition of functionalized carbons into the electrically        insulating flaky carbon layer 4M04, such as carbon        functionalized with silicon hydrides and/or nitrogen hydrides,        be included or deposited over the electrically insulating flaky        carbon layer 4M04 to block the diffusion and migration of        polysulfide (PS) to the surface of Li metal exposed to the        electrolyte 4M08.

Moreover, the addition of specific polymers/crosslinkers (such as anyone or more of those referenced by the table 4D00 shown in FIG. 4D) canimprove mechanical properties of the electrically insulating flakycarbon layer 4M04, enhance Li ion transport and/or flux (as shown by theone or more pathways 4M14 in FIG. 4M) across the electrically insulatingflaky carbon layer 4M04. Further examples of polymers that enhance Liion transport include poly (ethylene oxide) and poly(ethyleneimine),whereas examples of linkers that can be used to crosslink carbonstogether include inorganic linkers (such as borate, aluminate,silicate), multifunctional organic molecules (such as diamines, diols),polyurea, and high molecular weight (MW) carboxymethylcellulose CMC.

Additional or alternative methods of manufacturing and/or depositing theelectrically insulating flaky carbon layer 4M04 onto the protectedelectrode 4M00 include:

-   -   spray coating;    -   slurry casting the carbon layer onto the perforated film for a        better release;    -   slurry casting the carbon layer onto a separator for direct cell        assembly afterward without the need to release; and    -   vacuum filtration of the electrically insulating flaky carbon        layer 4M04 onto a separator with or without        calendaring-lamination.

Any one or more of the A-SEI described with reference to the A-SEIprotected anode 4B00 shown in FIG. 4B or the protected electrode 4M00(protected by the electrically insulating flaky carbon layer 4M04) canbe teardown of competitors' cells to reveal interfacial coatings on theanode surface which can be further analyzed by a variety of testingmethodologies such as:

-   -   analysis of tear down using X-ray powder diffraction (XRD), mass        spectrometry, and visual detection by observation through a        scanning electron microscope will reveal material properties        inherent within the observed or evaluated structure such as the        flake-like morphology of included carbons; and    -   mechanical testing of competitors' anodes will reveal        similarities to any one or more of the presently disclosed        protective carbon interface layers.

EXAMPLES

FIG. 4O is a photograph of an example protective carbon interface (PCI)4O00 suitable for deposition on a Li anode, such as that shown byprotected electrode 4M00 in FIG. 4M, according to some implementations.The PCI layer can include a ratio of different carbon allotropes thatare mixed together to create a uniform dispersion that is thentransferred directly by roll transfer on the Li metal foil, such as thatdescribed by the roll-to-roll apparatus 4N00 shown in FIG. 4N. The PCIlayer 4O00 maintains a relatively stable mean charge voltage which isindicative that no undesirable parasitic side reactions taking placewithin a so-equipped battery cell during cyclical operation.

FIG. 4P shows a graph 4P00 of electrode specific capacity performance ofan Li anode protected by the protective carbon interface (PCI) 4O00shown in FIG. 4O compared against a reference pure Li metal electrodeover cycle number, according to some implementations. As shown, thereference Li metal electrode exhibits a sharp decrease in capacity afterapproximately 25 cycles. The sharp decrease in capacity results fromparasitic reactions occurring on the surface of the Li anode exposed tothe electrolyte resulting in dendritic formation on the surface of theLi anode and correspondingly increasing the impedance of the anode. Incontract, PCI layer prevents the sudden sharp drop off in capacityresulting from the interface layer being able to prevent high impedance.

FIG. 4Q shows a graph 4Q00 of coulombic efficiency of an Li anodeprotected by the protective carbon interface (PCI) 4O00 shown in FIG. 4Ocompared against a reference pure Li metal electrode over cycle number,according to some implementations. The coulombic efficiency shown inFIG. 4Q indicates that the reference Li metal electrode experiences asharp aberration (such as a decrease) in efficiency from cycle 30 (asshown by erratic behavior of the data points), whereas the PCI 4O00maintains a steady level of efficiency through out cycling. The erraticefficiency data in the reference Li metal electrode corresponds to highlevels of Li dendritic growth. This is further confirmed by the meancharge voltage data shown in FIG. 4R.

FIG. 4R shows a graph 4R00 of mean charge voltage of an Li anodeprotected by the protective carbon interface (PCI) compared against areference pure Li metal electrode over cycle number, according to someimplementations. As shown, the mean charge voltage of the reference Limetal electrode increases rapidly whereas the PCO layer (correspondingto the PCI 4O00 shown in FIG. 4O) remains relatively constant,indicating a lack of Li dendritic growth.

FIG. 4S shows another graph 4S00 of cycling data for various full cells(with limited supply lithium), each in a coin cell format. Electrodespecific capacity (in mAh/g) performance of an Li anode protected by theprotective carbon interface (PCI) is compared against a nanodiamondlayer, a reference pure Li metal electrode, and a non-uniform interfacelayer over cycle number, according to some implementations. As shown,without the protective interface layer, the Li reference fades rapidly.The protective carbon interface layer (corresponding to the PCI 4O00shown in FIG. 4O) showed the best capacity retention followed bynanodiamond layer. The non-uniform (carbon) interface layer with visibledefects on the surface actually performed worse than Li lithiumreference, suggesting the uniform coverage of lithium surface and theintegrity of the interface layer are critical parameters.

FIG. 4T shows a photograph of a reference cell teardown 4T00 of anexample reference lithium pouch cell showing a high degree of dendriticgrowth (shown in a region 4T02) into the separator. The dendritic growthhere is shown as a transfer (growth) of the black mossy structure in theregion 4T02.

FIG. 4U shows a photograph of a teardown 4U00 of an examplecarbon-containing layer protected Li anode, such as the protectedelectrode 4M00 shown in FIG. 4M, showing a lack of the mossy blackprotrusions shown in the region 4T02 of the reference cell teardown 4T00shown in FIG. 4T. Instead, teardown 4U00 shows only a few trace spots ofdelaminated PCI that adhered to the separator upon deconstruction.

Conversely, depicted in FIG. 6 the separator doesn't not have any themossy black protrusions found in the reference cell. Rather it has a fewspots of delaminated LPCI that stuck to the separator upondeconstruction.

Integration with Li Ion (and Li S) Battery Electrode

An example Li ion, or Li S, secondary electrochemical cell system 500 isshown in FIG. 5 , having an anode 501 and cathode 502 separated by aseparator 517. Any one or more of the anode 501 and the cathode 502 canbe substantially formed by the lithiated carbon scaffold 400A shown inFIG. 4A and represented here in a simplified representation of largerand smaller carbon particles 509, all of which are at least partiallyconfine Li ion-conducting electrolyte solution 518 containingdissociated Li ion conducting salts 505 as shown. The separator, aporous membrane to electrically isolate the anode 501 and the cathode502 from each other, is also in the position showed. Single Li ionsmigrate through pathway 507 back and forth between the electrodes of theLi ion-battery during discharge-charge cycles and are intercalated intocarbon-based active materials forming any one or more of the anode 501and the cathode 502 for confinement therein as necessary for optimalsecondary electrochemical cell 500 performance.

Electrolytes, such as the electrolyte solution 518, can be generallycategorized into several broad categories, including liquid electrolytesand solid electrolytes. The liquid electrolyte is the most commonly usedelectrolyte system across many conventional batteries due to its highionic conductivity, low surface tension, low interface impedance, andgood wettability within the electrode. In Li S battery systems, liquidelectrolytes dominate because they help compensate for a lot of thepotentially encountered poor electrochemical kinetics of S and lithiumsulfide (Li₂S). In Li S systems, a liquid electrolyte containing anether-based solvent can be used, since because ether-based solvents,unlike carbonates, do not negatively react with S and generally havebetter Li ionic transport properties. A potential drawback of usingether-based electrolytes includes solubility of long chain polysulfides(PS), which can eventually lead to Li S electrochemical cell degradationdue to PS shuttle, migration, and volumetric expansion of the cathodeleading to compromise of its structural integrity.

Outside of conventional liquid-phase electrolytes, solid stateelectrolytes can be potentially configured to stop formation and growthof Li dendrites, and to stop the PS shuttle as solid-state electrolyteseffectively convert Li S systems from a multi-phase system to asingle-phase system, resulting in no internal shorting, no leakage ofelectrolytes, and non-flammability. Solid polymer electrolytes can bedefined as a porous membrane possessing the ability to transport Li ionsacross that membrane. A solid electrolyte can be further categorizedinto solid polymer electrolytes, gel polymer electrolytes, andnon-polymer electrolytes. A solid polymer electrolyte can be composed ofa lithium salt dissolved in a high molecular weight polymer host. Commonpolymer hosts used are polyethylene glycol (PEO), polyvinylidenefluoride or polyvinylidene difluoride (PVDF), poly(p-phenylene oxide) orpoly (PPO), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP),and poly(methyl methacrylate) (PMMA), etc.

Gel polymer electrolytes can be similar to solid polymer electrolytes inthat they have a high molecular weight polymer, but also include aliquid component tightly trapped within the polymer matrix. Gel polymerelectrolytes, in some implementations, were developed to compensate forpoor ionic conductivity observed in solid polymer electrolytes. Overother forms of solid electrolytes, non-polymer solid electrolytes haveadvantages of high thermal and chemical stability.

Non-polymer solid electrolytes consist of a ceramic and commonly foundnon polymer electrolytes include LIthium Super Ionic CONductor(LISICON), Li₇La₃Zr₂O₁₂ (LLZO),Li₇La_(2.75)Cao_(0.25)Zr_(1.75)Nb_(0.25)O₁₂ (LLCZN), Garnet, andGe-Doped Li_(0.33)La_(0.56)TiO₃ (Ge-LLTO) Perovskite, etc., and can havea thickness in a range of approximately 0.5 μm to 40 μm, which can beconfigured to substantially prevent any one or more of Li dendriteformation or growth. Nevertheless, some solid electrolytes can sufferfrom certain challenges including relatively poor Li ionic conductivityand weight. At the thicknesses needed to prevent Li dendrite growth,observed ionic impedance can so high that a so-equipped Li ion or Li Sbattery may not function as desired, while at the thicknesses needed tohave acceptable Li ionic conductivities, Li dendrite growth may not beprevented.

During discharging, Li is deintercalated from the anode 501. The activematerials of the cathode 502 can include mixed oxides. Active materialsof the anode 501 can include primarily graphite and amorphous carboncompounds including those presented herein. These are the materials intowhich the Li is intercalated.

The Li ion conducting salt 505 can dissociate to provide mobile Li ionsavailable for intercalation into any one or more of the uniquecarbon-based structures disclosed herein that can be incorporated intoany or more of the anode 501 or the cathode 502 as a formative materialto achieve specific capacity retention capability exceeding 1,100 mAh/gor more as facilitated by the contiguous microstructures 107E. Li ionsform complexes and/or compounds with S in Li S systems and aretemporarily confined during charge-discharge cycles at levels nototherwise achievable through conventional unorganized carbon structuresthat require adhesive definition and combination via a binder, which canas discussed earlier also inhibit overall battery performance andlongevity.

The pores 105E of the contiguous microstructures 107E shown in FIG. 1E,which may form the carbon based particle 100A, 100D, 402A and/or thelike and be used to produce conductive graded film layers for any one ormore of the anode 501 or the cathode 502 can be defined, duringsynthesis, to include a micropore volume (pores<1.5 nm). Sulfur (S) isinfused via capillary force into the pores 105E where the S is beconfined. Successful microconfinement of sulfur would prevent dissolvedpolysulfides (PS), as presented earlier regarding Li S systemsgenerally, from reprecipitating outside of their original pores. Toachieve an active carbon composite capable of holding achievablequantities of S, a pore volume of 1.7 cc/g with all 1.7 cc/g attributedto pores with an opening<1.5 nm may be needed.

Operationally, in either Li ion or Li S systems, Li ions migrate fromthe anode 501 through the electrolyte 518 and the separator 517 to thecathode 502. Here, molten Li metal 514 micro-confined, as shown inenlarged areas 516 and 513, within few-layer graphene sheets 515associated with any of the presently disclosed carbon-based structuresused as formative materials for the anode 501 or the cathode 502. MoltenLi metal may dissociate in the anode 501 pursuant to the followingequation (8):FLG-Li→FLG+Li+e−  (8)

Eq. (1) shows electrons 506 and 511 discharging 508 to power an externalload such that Li ions 512 migrating to cathode 502 return to athermodynamically favored position within a cobalt oxide-based latticepursuant to the following equation (9):xLi⁺ +xe ⁻+Li_(1-x)CoO₂→LiCoO₂.  (9)During charging, this process is reversed, where lithium ions 505return-migrate from the cathode 502 through the electrolyte 518 and theseparator 517 to the anode 501.

Disclosed carbon-based structures, referring to the surprising favorablespecific capacity values made possible by the unique multi-modalhierarchical structures of carbon-based particle 100A, 100D and/orderivatives thereof, including carbon scaffold 300B and lithiated carbonscaffold 400A, any one or more of which can be configured to build upontraditional advantages offered by Li ion technology. Compared to sodiumor potassium ions, the relatively smaller Li ion exhibits asignificantly faster kinetics in the different oxidic cathode materials.Another difference includes that, as opposed to other alkaline metals,Li ions can intercalate and deintercalate reversibly in graphite andsilicon (Si). And, a lithiated graphite electrode enables higher cellvoltages. Disclosed carbon-based material therefore enhance the easethrough which Li ions can intercalate and deintercalate reversiblybetween graphene sheets, due to the unique lay-out of few-layer graphene(FLG), such as 5-15 layers of graphene in a generally horizontallystacked configuration 101C, as employed in carbon-based particle 100Aand/or the like, and are suitable for application hardcase, pouch cell,and prismatic applications.

Stabilization of Artificial Solid-Electrolyte Interface (SEI) Films byDoping

At present, current Li ion batteries form a protective passivation layer(such as the passivation layer 418A shown in FIG. 4A), or solidelectrolyte interface (SEI), at the electrode surface exposed toelectrolyte during a pre-conditioning step when the electrolyte is firstintroduced followed by initial discharge and charge steps. Althoughelectrolyte chemistry and pre-conditioning protocols, such ascharge/discharge rate and overvoltage, may be adjusted to optimize filmpassivation, referring to SEI formation, conventional film layersincorporated into electrodes can still be chemically and mechanicallyunstable.

Referring now to FIG. 6A, specific elements 602A may be introduced tothe aforementioned carbon materials 600A by doping. The elements 602A,such as silicon, sulfur, nitrogen, phosphorous at an example exposedelectrode surface 601A can be coated at specified levels of conformalcoverage onto the electrode surfaces 601A of the carbon structures, suchas ranging from sparse decoration to complete conformal coverage.Precedence for formation of stable solid-state electrolyte ionconducting layers have been reported in literature; referring tosulfide-based thioLISCONs, defined as Lithium Sulfur CONductors havingthe chemical formula Li_(3.25)Ge_(0.25)P_(0.75)S₄, and phosphate-basedNASCIONs, such as sodium (Na) Super Ionic CONductor, which usuallyrefers to a family of solids with the chemical formulaNa_(1+x)Zr₂Si_(x)P_(3−x)O₁₂, 0<x<3 and the acronym is also used forsimilar compounds where Na, Zr and/or Si are replaced by isovalentelements. The formation of a stabilizing solid state passivation layeras explained here include doping specific elements 602A the electrodesurface 601A can be engineered prior to battery assembly and therebydecouple the formation process of a stable solid state ion conductinglayer from the reduction/oxidation events that occur when in contactwith electrolyte, as encountered in current Li-ion battery fabricationwhich still often suffers from long term stable operation.

Manufacturing with Slurry Cast Techniques

In combination with conductive particles, such as carbon black, andoptionally polymer binders and solvent, such as NMP, any one or more ofthe tuned 3D hierarchical graphene-based particles disclosed herein canbe directly incorporated into conventional slurry cast electrodefabrication processes as follows:

-   -   an active graphene based (FLG) substitute for graphite        particles, in the case of the anode; and/or    -   infused with active sulfur (S) in the case of the cathode.        The 3D graphene particles provide high specific capacity        graphene building blocks with interconnected mesoporous ionic        conducting channels for rapid Li ion transport along with carbon        black and binder to ensure electrical conducting pathways, such        as defined by the graphene sheets 101B used as a formative        material for the contiguous microstructures 107E, which also        provide mechanical integrity.

Disclosed carbon materials can be pre-lithiated by ball milling and/orpost thermal annealing and electrochemical reduction from a thirdelectrode, at:

-   -   a relatively low concentration to offset first charge Li loss in        conventional oxide cathode cell; or    -   at a relatively higher concentration to increase overall        specific capacity for both oxide and alternative cathode        configurations, and then slurry cast into electrodes.

FIGS. 6B1 and 6B2 show a schematic diagram comparing a chemicallynon-reactive system 600B1 against a chemically reactive system 600B2 inthe context of active material infiltration and confinement of lithium(Li) within the active material, according to some implementations.Although configurations where molten Li metal is infiltrated into anyone or more of the presently disclosed carbon-based structures shown inFIG. 1A through FIG. 1E, such as the contiguous microstructures 107E,alternative or additional implementations provide for the infusion ofmolten Li metal droplets, in a vapor phase, into pores, such as thepores 105E. In the chemically non-reactive system 600B1, Li metaldroplets are prepared, or are expected to, fail to react with carbon oncontact with exposed carbon surface due to, for example, Li-phobicity ofthe carbon. Regardless, infusion of vapor-phase Li droplets at anintrinsic contact angle (θ) between approximately 50° and 90° canprovide a balance between competing liquid-to-solid adhesive forces,such as adhesion observed between liquid-phase molten Li droplets (suchas that used to provide the Li ions 108E) and solid-phase carbonproportional to (γ_(sl)) cohesive forces in liquid (γ_(lv)).

Wetting, occurring between the vapor-phase Li and solid-phase carbon, isdefined as the ability of a liquid to maintain contact with a solidsurface, resulting from intermolecular interactions when the two arebrought together where the degree of wetting, or wettability, can bedetermined by a force balance between adhesive and cohesive forces.Desirable degrees of wetting can occur where adhesive energy is nearcohesive energy, such as with tightly-held bonds, as encountered inliquid-phase metals dispersed on solid-phase metals, or as seen insemiconductors including silicon (Si), germanium (Ge), or siliconcarbide (SiC), as well as ceramics including any one or more ofcarbides, nitrides, or borides, which can demonstrate metallic-likebehavior near exposed surfaces. And usage of liquid-phase metals with arelatively high solubility for atmospheric contaminants, such as oxygen(O), nitrogen (N), or moisture (H₂O vapor), or carbon, can reduce thecontact angle observed or needed during wetting at contaminated solidsurfaces, or at pure-carbon surfaces.

In the chemically reactive system 600B2, wetting of a carbon surfacelayer 602B2, such as that encountered on surfaces of the carbon-basedparticle 100A exposed to Li metal, can be accompanied by chemicalreaction occurring at that interface, such as the dissolution of solidcarbon materials or the formation of a new 3D layer 604B2 or compoundinvolving at least partial consumption of the underlying carbon surfacelayer 601B2. The addition of dopants, tuned by type and concentration,at the carbon surface layer 602B2 can also affect a degree or extent ofwetting, as shown by the various fluid positions 606B2, 608B2 and 610B2,showing a molten Li droplet with very little wetting at position 606B2with progressively greater wetting at positions 608B2 and 610B2,respectively. The formation of the new 3D layer 604B2 can, in someimplementations, alter properties of the underlying carbon surface layer602B2, such properties including electrical conductivity, or canotherwise limit, by pinching off, infiltration into porous media by theformation of a volumetrically expanded reaction product, shown as thenew 3D layer 604B2.

For either the chemically non-reactive system 600B1 or the chemicallyreactive system 600B2, decreasing the contact angle of liquid Li metaldroplet beads, such as that shown in position 610B2, can promote wettingof the underlying carbon surface layer 602B2. And, for configurationswhere the carbon surface layer 602B2 incorporates adsorbed or chemicallybonded oxygen (O), the addition of elements, such as that also referredto as getters, with a high O solubility can reduce or otherwise controlO activity at the new 3D layer 601B2. For solid variants of the carbonsurface layer 602B2, the addition of elements such as nickel (Ni), iron(Fe), or others to liquid-phase metals having a high carbon solubilitycan insure a relatively high surface activity or affinity.

FIG. 7 shows an example process workflow where molten Li metal isinfiltrated into void spaces between carbon agglomerations to initiate areaction at exposed carbon surfaces, according to some implementations.Considerations for infiltrating Li metal 704, 706 into packed carbonscaffold 702, which may be incorporated within or otherwise provide aformative material for any one or more of the presently disclosedcarbon-based structures such as carbon particle 100A shown in FIG. 1A orcontiguous microstructures 107E shown in FIG. 1E, are shown in aninfiltration process workflow schematic 700. Surface conditions of thecarbon scaffold 702 can be tuned prior to infiltration by molten Limetal, which can enter into the carbon scaffold 702 by any one or moreof capillary infusion using molten Li metal in a liquid-phase, orinfusion of molten Li metal droplets suspended in air forming a Li metalvapor. Precise tuning of the following conditions at carbon scaffold 702surfaces exposed to incoming Li include control of:

-   -   atmospheric contaminants such as moisture (H₂O vapor), oxygen        (O), nitrogen (N), and hydrocarbons configured to confine or        contain physiosorbed or chemisorbed O;    -   formation of nitrogen bonds at surface during post plasma        treatment; and    -   purity of lithium metal, such as control of prevalent surface        oxides, nitrides, and carbonates.

Li infiltration can be initiated by capillary infusion of molten Limetal 704, 706 to intersperse within the carbon scaffold 702 as well asfill, forming a lithiated carbon compound 708, void spaces of the packedcarbon scaffold 702. Procedures can be followed by a non-reactive Liwetting infiltration and post-reaction processed. Various specificprocess options exist through which Li can be infiltrated into thecarbon scaffold 702, including:

-   -   usage of molten Li metal to initiate a reaction at exposed        carbon surfaces—assuming conditions of controlled hydroxyl group        (OH) and oxygen (O) adsorption on exposed surfaces of the carbon        scaffold 702, such as one or more        lithiophilically-functionalized surfaces that are configured to        provide Li adsorption centers, thermal oxide reduction or        exposure of the carbon scaffold 702 to above-positioned pristine        molten Li metal vapor for a duration of, for example 30 to 45        seconds at approximately 200° C., can initiate a chemical        reaction at exposed surfaces of the carbon scaffold 702 to form        a lithiophilic surface, such as LiC₆;    -   coating of exposed carbon surfaces with surface active elements        to control surface contaminants on interfacial regions of molten        Li metal and exposed carbon—fluxing elements can be used to        break oxide skull and/or facilitate melting of halogens        including fluorine (F), oxide getters can be used to reduce        oxide (Ti, other);    -   promoting alloying and wetting by coating exposed carbon        surfaces with elements, such as metals, having a lower surface        energy than Li and/or elements such as silicon (Si) aluminum        (Al) that facilitate Li wetting and/or infiltration; and    -   incorporating metal powders, or metal containing compounds, such        as silicon carbide (SiC), and others, in carbon preform, such        as, SiNP, Ni, and other, to serve as binder and facilitate        wetting infiltration allowing for the control of a ratio of        metal to carbon dependent on non-reactive wetting parameters.        FIG. 8A shows an equation for a rate of infiltration a        carbon-based structure with void spacing therein defined by any        one or more of the 3D carbon-based particles shown in FIG. 1A        through FIG. 1F, according to some implementations.

FIG. 8A shows an equation for modelling a rate of Li infiltration intoany one or more of the porous regions of the currently presentedcarbon-based structures, such as the pores 105E and contiguous pathways107E shown in FIG. IE of the carbon-based particle 100A shown in FIG.1A. The rate of infiltration can be controlled by the non-reactiveviscous resistance of liquid metal, such as molten Li metal, followed bya chemical reaction between the liquid metal contacting the carbon toyield carbide pursuant to Washburn's equation 800A shown in FIG. 8A,where σ and η are surface tension and viscosity of liquid, respectively,θ is the contact angle and r_(eff) is the effective pore radius ofpores, such as the pores 105E shown in FIG. 1E, that can be interspersedthroughout a carbon-based scaffold, such as the carbon-based scaffold702 shown in FIG. 7 . Therefore, as can be seen by the variouscoefficients used in the Washburn's equation 800A, capillary flow isdescribed by modelling the carbon-based preform structure as atheoretical bundle of parallel cylindrical tubes to effectivelyrepresent imbibition into porous materials.

FIG. 8B shows a non-reactive system 800B including a non-wettingconfiguration 802B and a spontaneous wetting configuration 804B,according to some implementations. For instance:

-   -   in the non-wetting configuration 802B, a pressure (P₀) is        applied to overcome capillary pressure, such as the pressure        between two immiscible fluids in a thin tube, resulting from the        interactions of forces between the fluids and solid walls of the        tube, and can be limited by viscous friction, such as that        established and characterized by the Washburn's equation 800A; L        can denote a liquid-phase Li layer, such as that provided by        molten Li metal, S can denote solid carbon surfaces exposed to        L, θ can denote the contact angle of L to S, and V can denote        viscous friction and characterized by the Washburn's equation        800A at the contact region of L to S;    -   in the spontaneous wetting configuration 804B, θ is maintained        at an angle of <60° to achieve non-reactive Li infiltration of        the carbon-based scaffold; and    -   any one or more of the non-wetting configuration 802B or the        spontaneous wetting configuration 804B can be incorporated in or        otherwise implemented in an example carbon-based scaffold 806B,        which may be a formative part of any one or more of the        presently disclosed carbon-based structures.

FIG. 8C shows a reactive system 800C including a wettable reactiveproduct layer configuration 802C and a non-wettable surface layerconfiguration 804B, according to some implementations. The wettablereactive product layer configuration 802C can involve the formation of anew 3D layer 806C similar to that discussed earlier with relation to thechemically reactive system 600B2 shown in FIG. 6B2, where the formationof the new 3D layer 604B2 or compound involves at least partialconsumption of the underlying carbon surface layer 601B2. Here the solidcarbon material S can be at least partially consumed to produce orgenerate the new 3D layer 806C which can be or include LiC₆. Incontrast, in the non-wettable surface layer configuration 804B, surfacesof S immediately facing, such as in the vertical direction, L are notreactive such that encroachment of L into capillary, tubular, openregions result in consumptive reaction with S to yield a new 3D layer808C only along those capillary open regions.

FIG. 9 shows a flowchart 900 for a method of lithiating and alloying acarbon-based structure, according to some implementations. At block 902,oxide thermal decomposition can be used to initiate surface interfacereaction by lithium (Li) vapor pressure to activate surface of carbon inpacked preform. At block 904, surface active elements compounds, in theexample of Li film infiltration into a metal substrate, can beevaporated to breakdown oxide flux and/or promote wetting. At block 906,alloying elements, such as silicon (Si), aluminum (Al), and potassium(K), can be incorporated as part of the infiltration process to promoteinfiltration/manage oxygen activity at interface.

FIG. 10A shows a flowchart for a method 1000A of preparing acarbon-based structure to undergo a lithiation operation, according tosome implementations. At block 1002A, procedures can be established fortesting lithium foil/powder preforms. At block 1004A, of proxy metalpowder preform can be used to promote non-reactive infiltration whileunderstanding reproducible protocols for managing lithium, such assurface pre-treatment/management of impurities. At block 1006A, carbonsurface activity/pre-treatment protocols can be evaluated by measuringthermal activation response through various techniques includingthermogravimetric analysis (TGA) and/or differential scanningcalorimetry (DSC).

FIG. 10B shows a flowchart for another method 1000B of preparing Limaterials suitable for usage in a lithiation operation, according tosome implementations. At block 1002B, heater platens can be calibrated,and a thermal profiling of materials can be conducted. At block 1004B, aglove box environment can be determined, such as involving conditions orsettings for moisture and oxygen before, during, and after testing. Atblock 1006B, sample can be prepared from any one or more of lithium foiland/or evaporated lithium on metal foil, carbon powder, and others.

FIG. 10C shows a flowchart for a method 1000C of nucleating a pluralityof carbon particles at a first concentration level. At block 1002C aplurality of carbon particles can be nucleated at a first concentrationlevel configured to form a first film on a sacrificial substrate, eachof the carbon particles comprising a plurality of aggregates including aplurality of few layer graphene sheets fused together. At block 1004C aporous structure can be formed based on the plurality of few layergraphene sheets fused together. At block 1006C, a molten Li metal can beinfused into the porous structure.

FIG. 10D shows a flowchart for a method 1000D of nucleating a pluralityof carbon particles at a second concentration level. At block 1002D, thecarbon particles can be nucleated at a second concentration level on thefirst film. At block 1004D, a second film can be formed based on thesecond concentration level of the carbon particles.

FIG. 10E shows a flowchart for a method 1000E of growing carbonparticles. At block 1002, carbon particles can be grown on aroll-to-roll processing apparatus.

FIG. 10F shows a flowchart for a method 1000F of evaporating the moltenLi metal. At block 1002E, the molten Li metal can be evaporated onto ametal foil. At block 1004E, the molten Li metal can be rolled from themetal foil into the porous structure.

FIG. 10G shows a flowchart for a method 1000G of preparing the anode toparticipate in a reversible migration of Li ions. At block 1002G, theanode can be prepared to participate in a reversible migration of Liions with a cathode. The cathode is prepared by any one or more ofchemical functionalization or sulfidation.

FIG. 10H shows a flowchart for a method 1000H of densifying a pluralityof graphene platelets. At block 1002H, a plurality of graphene plateletscan be densified on the void structure.

FIG. 10I shows a flowchart for a method 1000I of depositing a firstplurality of carbon particles to form a first film. At block 1002I, afirst plurality of carbon particles can be deposited to form a firstfilm on a substrate, the first film configured to provide a firstelectrical conductivity. At block 1004I, a plurality of 3D aggregatesformed of few layer graphene sheets can be orthogonally fused togetherconfigured to define a porous structure. At block 1006I, a porousarrangement can be formed in the porous structure. At block 1008I, amolten Li metal can be infused into the void structure.

FIG. 10J shows a flowchart for a method 1000J of depositing a secondplurality of carbon particles. At block 1002J, a second plurality ofcarbon particles can be deposited on the first film. At block 1004J, asecond film can be formed based on the second plurality of carbonparticles.

FIG. 10K shows a flowchart for a method 1000K of infiltrating the moltenLi metal. At block 1002K, the molten Li metal can be infiltrated in avapor phase into the void structure. At block 1004K, a chemical reactioncan be initiated between any one or more Li ions provided by the moltenLi metal and one or more exposed surfaces of the void structure. Atblock 1006K, one or more lithiophilic surfaces can be formed from theone or more exposed surfaces.

FIG. 10L shows a flowchart for a method 1000L of coating any one or moreof the lithiophilic surfaces. At block 1002L, any one or more of thelithiophilic surfaces can be coated with active elements including anyone or more of halogens and oxide getters including titanium (Ti).

FIG. 10M shows a flowchart for a method 1000M of coating any one or moreof the lithiophilic surfaces. At block 1002M, any one or more of thelithiophilic surfaces can be coated with any one or more elements havinga lower surface energy than Li including silicon (Si) or aluminum (Al).At block 1004M, a Li wetting enhancement can be facilitated of any oneor more of the lithiophilic surfaces with any one or more elementshaving a lower surface energy than Li.

FIG. 10N shows a flowchart for a method 1000N of creating a binder. Atblock 1002N, a binder can be created by incorporating any one or more ofa metal powder or a metal-containing compound including silicon carbide(SiC) into a carbon scaffold.

FIG. 10O shows a flowchart for a method 1000O of adding of a quantity ofdopants. At block 1002O, of a quantity of dopants can be at theinterface. At block 1004O, an extent of the Li wetting can be affectedcorresponding to the quantity of dopants.

FIG. 10P shows a flowchart for a method 1000P of control adsorption ofhydroxy (OH) or hydroxyl (OH) groups. At block 1002P, adsorption ofhydroxy (OH) or hydroxyl (OH) groups can be controlled at any of the oneor more exposed surfaces of the void structure.

FIG. 11A shows a flowchart for a method 1100A of Infuse lithium. Atblock 1102A, lithium can be infused by using roll-to-roll furnacebrazing or spontaneous infiltration. At block 1104A, a two-dimensional(2D) analog can be used with a 2D liquid gap filler. At block 1106A,infused lithium metal can be chemically reacted at a liquid-to-solidinterface with exposed carbon surfaces with controlled flux foractivation, increased and/or decreased surface tension, and controlledthermodynamic driving force. At block 1108A, rapid screening of lithiumwettability can be conducted with Li foil/carbon particle stacked on hotplate by using a halogen interlayer to breakdown Li₂O.

FIG. 11B shows a flowchart for a method 1100B of evaporating lithium(Li) onto a metal foil. At block 1102B, lithium can be evaporated onto ametal foil, which can act as a thermal conductor. At block 1104B, coppercan be optionally used as a current collector and/or tantalum forrelease to achieve minimal chemical interaction. At block 1106B, filmthickness can be tuned commensurate with pore volume in packedcarbon-based particles and-or structures.

FIG. 11C shows yet another flowchart for a method 1100C of preparing acarbon particle for lithiation, such as through process referred to aspre-lithiation. At block 1102C, foil on top of carbon particle packedbed or pre-lithiated and/or pre-formed can be oriented with ato-be-applied load, such as a calendar roll type, in dry roomenvironmental conditions. At block 1104C, overall isothermal-likeconditions, such as at approximately 180° C., and/or immediately belowthe Li melting point, can be created across Li and packed particles withrapid thermal spike at location of concentrated loading. At block 1106C,an exothermic reaction can be used to initiate infiltration followedwith a capillary driven fluid flow in porous carbon media takingadvantage of principles related to Darcy's law, Washburn, etc. withvariable permeability. The capillary driven fluid flow assumes noappreciable reaction product formation/build-up.

FIG. 12 shows a flowchart of a method 1200 of performing a Li infusionof a carbon particle during its formation with a vaporized Li, accordingto some implementations. At block 1202, metal, such as copper and/ortantalum, foil can be coated with lithium, such as in a vacuumevaporator; measured Li volume, such as thickness and density, can becommensurate with pore volume in packed particle layer. At block 1204,particles can be assembled into a packed film without binder, such asthrough size enlargement, creation of course granular material, such asfilm, from fines, where assembly techniques can include tumbling,pressure compaction, heat reaction, fusion, drying, agglomeration fromliquid suspensions, as well as electrostatic to form coin cell sizepucks. At block 1206, an innate carbon particle can be formed. At block1208, sp²/sp³ ratios of carbon during formation can be optimized tocorrespondingly increase lithium (Li) insertion and/or intercalation. Atblock 1210, impurity contamination, such as that caused by acetylene andother post plasma aromatics, can be reduced. At block 1212, posttreatment operations can be performed.

FIG. 13 shows a schematic diagram showing an idealized anode 1300configuration with 3D graphene-based nanostructures 1302 incorporatedtherein to provide structural definition to the anode 1300, according tosome implementations. The 3D graphene-based nanostructures 1302 can beincorporated into or provide structural definition to any one or more ofthe presently disclosed carbon-based structures, including the pores105E and/or the contiguous pathways 107E, both shown in FIG. 1E, and canconfine or otherwise retain metal dopants such as silicon (Si) 1312 andcreate surface-activated diffusional pathways 1316 to handle volumetricexpansion during Li ion 1306 alloying—de-alloying cycles, and to alsolimit electrolyte ingress. Silicon can redistribute, as shown in apathway 1310, into defects, pores, or wrinkles in few-layer graphenesheets as well as distributing, in a pathway 1308, into a binder 1304,such as highly polar polyacrylonitrile (PAN). Sulfur (S) doping can beperformed or occur at graphene 1314 to silicon contact regions orsurfaces to assist in Li complexing in Li S battery systems and relatedcharge-discharge cycles to achieve any one or more of the performancefigures quoted herein, including a specific capacity greater than 372mAh/g, which is ordinarily achievable as a theoretical maximum bygraphite alone. In some implementations, graphene oxide can be used inaddition or in the alternative to few-layer graphene, and the Li Ssystem can be immersed in a LiPF₆ liquid-phase electrolyte.

The anode 1300 can be configured with existing or to-be-developed futurecarbon-based materials, offering backward-compatibility. Thesurface-activated diffusional pathways 1316 can host Li metal, while Lican also be intercalated in between pairs of few layer graphene sheets.Pore sizes of carbon materials can be tuned in the anode 1300 to achievecertain distributions or containment levels of Li, as well as Li ionflow reversibility, and can be created with either amorphous orcrystalline carbon structures.

Pre-lithiation of the anode 1300 can initially include electrochemicalor direct contact to molten Li metal to later transition to direct vaporinfusion techniques. Carbon structures used as a formative material toconstruct the anode 1300 can be direct deposited as a film of particles,as substantially described earlier, or from powders. A rate of Lieffusion can match a rate of Li insertion within the anode 1300 to avoidexcess Li deposited or condensed carbon surfaces exposed to incoming Li.And, production and cost metric considerations of the anode 1300 caninclude:

-   -   producing carbon-based materials as low-cost powders, rather        than films, that are configured to be dropped into to existing        Li ion or Li S battery fabrications;    -   direct deposition, independent of a binder, of carbon-based        films on drums; and    -   Li infusion into carbon-based particles and structures, such as        slurry cast films/binders, evaporation techniques can be used to        purify or dry carbons.

Li infusion of the anode 1300 can include the following proceduresestablished by known roll-to-roll furnace brazing and/or spontaneousinfiltration techniques, including any one or more of the following:

-   -   use a two-dimensional (2D) analog with 2D liquid gap filler;    -   liquid to solid chemical reactions, using flux for activation;    -   increase of a proportion of solid to viscous surface area and        decrease a proportion of liquid to viscous surface area to        control and tune surface tension and/or thermodynamic driving        forces; and    -   screen Li wettability with Li foil/carbon particle stack on a        hot plate using a halogen interlayer to breakdown any formed        lithium oxide (Li₂O).

Li infusion of the anode 1300 can also include the following procedures,techniques, or implementations related to the evaporation of Li onto ametal foil configured to act as a thermal conductor:

-   -   selection of copper (Cu) for use as current collector in Li ion        or Li S battery systems incorporating the anode 1300;    -   tantalum (Ta) interspersed within the anode 1300 for Li ion        release resulting in minimal overall chemical interactions; and    -   production of carbon-based film thicknesses commensurate with        pore volume in packed particles.

Moreover, Li infusion of the anode 1300 can also include the followingprocedures, techniques, or implementations related to the orienting ofLi and Ta foil on top of a carbon particle packed in a bed configurationthat can be prepared to receive a load or pressure provided by arotating calendar roll type drum in dry room environmental conditions:

-   -   forward rotation of a calendaring roll or drum wrapped with a        layer of Ta foil that is further wrapped in Li foil compresses        against carbon particles prepared as a thin layer of material,        which is placed on a copper foil, with heat applied by the        calendaring roll and to the Cu foil to melt Li and create molten        Li metal that infiltrates into the carbon particles;    -   creation of overall isothermal conditions, such as at        approximately 180° C., just below the Li melting point across        infiltrated Li and packed carbon particles;    -   observing a rapid thermal spike at location of concentrated Li        loading; and    -   Li infiltration with an exothermic reaction with capillary        driven molten Li metal fluid flow in porous carbon media as        governed by any one or more of Darcy's law, Washburn's equation,        etc., with variable permeability, processes assume no        appreciable reaction product formation or build-up.

Still further, Li infusion of the anode 1300 can also include thefollowing procedures, techniques, or implementations:

-   -   coat metal, such as copper (Cu) and/or tantalum (Ta) foil with        lithium Li in a vacuum evaporator; control Li volume, such as        thickness and density, commensurate with pore volume in a packed        carbon particle layer or film;    -   assemble carbon particles into a packed film without a binder,        although binder options could be considered assuming there is        not interaction with molten Li and that the proposed binder        could be easily removed after Li infiltration;    -   enlargement and/or creation of course granular carbon material,        such as a film, from carbon fines, such as by tumbling, pressure        compaction, heat reaction, fusion, drying, agglomeration from        liquid suspensions, as well as electrostatic to generate coin        cell size structures shaped as pucks;    -   collecting or screening any of the aforementioned materials        within a reactor;    -   performing post microwave sintering, or fusing; and    -   performing partial compaction into a puck or tablet independent        of a carbon die.

Innate carbon particle formation of few layer graphene and other carbonsused to form the anode 1300 can include:

-   -   optimizing sp² and/or sp³ carbon structure formation to increase        lithium insertion/intercalation; and    -   reducing impurity contamination, such as acetylene and other        post plasma aromatics.

Post treatment methods can include:

-   -   washing, such as removing aromatics;    -   baking carbons for a duration of approximately 3 hours at        approximately 500° C. to remove adsorbed moisture and/or oxygen;        and    -   nitriding and/or treating carbons with silicon monoxide.

Factors influencing Li infiltration into carbon structures of the anode1300 can include:

-   -   precursor volume;    -   melt temperature, such as from approximately 180° C. to 380° C.;    -   particle post treatment, such as at a carbon surface exposed to        contact with Li;    -   mechanical pressure;    -   graphene properties, such few layer, or sheet size;    -   carbon structure morphology, including pore size, volume,        distribution; and    -   surface activation.

Carbon structure response to Li infiltration can include:

-   -   spontaneous infiltration;    -   accumulation of excess Li material to achieve a balanced mass        proportionate to Li input; and    -   extent of infiltration based on the ratio of carbon surface area        exposed to incoming Li compared against the overall volume of        the carbon structure.

FIG. 14 shows a silicon and carbon (Si—C) anode performance comparinganode specific capacity in mAh/g over charge-discharge cycle number,according to some implementations. The various series shown including426, 459, 462, 486, 487, and 401 can include variants and/orpreparations similar to the anode 1300 shown in FIG. 13 or any one ormore of the carbon structures shown in FIG. 1A through FIG. 1Fincorporated within a Li ion or Li S system anode. As shown, thepresently disclosed carbon structures can uniformly yield specificcapacity values significantly higher than 372 mAh/g as commonlyassociated with a graphite anode.

FIGS. 15 and 16 show schematic diagrams related to an idealized cathodeconfiguration 1500, shown in FIG. 15 , featuring dispersed lithiumsulfide (Li₂S) nanoparticles in graphene sheets held together by a PANtype binder and submerged in LiTFSI electrolyte solution to providefacile Li ionic transport and electric conduction as well as mitigationand control of polysulfides (PS) generated in Li S battery systemcharge-discharge cycles, according to some implementations. Theidealized cathode configuration 1500 can be implemented at least in partwith any one or more of the presently disclosed carbon structures,including to form the pores 105E and/or contiguous microstructures 107Eshown in FIGS. 1E, in Li S battery systems. FIG. 16 shows an examplein-situ 3D nanostructured few-layer graphene material 1600, which may beincorporated to provide structural definition to any one or more of thepresently disclosed carbon structures. In some implementations, a stackof few-layer graphene sheets 1602 can include milled, sulfur impregnatedgraphene heated at a two-stage high temperature (HT) process to 250° C.and 350° C. The stack of few-layer graphene sheets 1602 can beinfiltrated by Li such as that provided by lithium triethylborohydride(LiEt₃BH) in THF solution or n-butyllithium provided in an inert argon(Ar) atmosphere to provide a Li source 1604 by any one or more of theaforementioned Li infiltration techniques. The Li infiltrated stack offew-layer graphene sheets 1602 can undergo HT vacuum treatment at 10hours at 110° C. to in-situ form Li₂S in pores, such as the pores 105Eshown in FIG. 1E, where such Li₂S is involved in Li S electrochemicalcell functioning as described earlier.

FIG. 17A shows an enlarged perspective cut-away view of carbon-basedparticle 100A, 100E and/or the like. Individual ligaments 1702A formedfrom as discussed in connection with carbon-based particle 100A shown inFIG. 1A through FIG. 1E, contact surfaces and/or regions betweenelectrically conductive interconnected agglomerations of graphene sheets101B, may extend to form a lattice and/or tree-like branched structureof section 1700A through which Li ions (Li+) 1704A may be intercalated,inserted in between individual gradient layers of section 1700Acomprising, 3D bundles of graphene sheets 101B. Electric current may beconducted via flow of electrons through contact surfaces and/or regionsbetween interconnected 3D bundles of graphene sheets 101B. Li ions, mayflow through pores 1710A, sized at a larger size of the bi-modaldistribution of voids or pores as described in FIG. 1A through 1E on theorder or 20 to 50 nanometers, or be confined, such as via chemicalmicro-confinement, in pores sized generally on the order of 1 to 3nanometers.

Therefore, Li ion flow may be finely controlled or tuned in carbon-basedparticle 100A to, for example, to be diametrically opposite to electronflow as needed to facilitate an electrochemical gradient that may benecessary for electricity conduction and/or electron flow throughcontact points and/or regions of 3D bundles of graphene sheets 101B.Spacing between individual carbon-based ligaments may be set a 0.1 μm.Those skilled in the art will appreciate that the dimension of 0.1 μm isprovided as an example only and that other suitable similar ordissimilar dimensions may exist in section 1700A of carbon-basedparticle 100A.

Section 1700A may be formed of 3D bundles of graphene sheets 101B thatare sintered together with each other to form a configuration wherethere are no completely open channels such that electricity isnecessarily conducted through contact points and/or regions ofinterconnected 3D bundles of graphene sheets 101B. Thus, liquid passingthrough voids 1704A, and the conductive nature of carbon-to-carbonbonding facilitates a connection of carbon-based materials to othercarbon-based materials without the necessity of a chemical binder and/orchemical binding material or agent, many of which resulting inundesirable chemistries or side effects regarding functionality ofcarbon-based particle 100A.

Open porous scaffold 102A of carbon-based particle 100A presents adeparture from traditional industry-standard battery electrodes that mayinvolve slurry-cast boulders, relatively large particles, organizedhaphazardly on a substrate, such boulders typically requiring a binderto be held together to conduct electricity there-through. Open porousscaffold 102A defined by hierarchical pores 101A and/or the contiguousmicrostructures 107E of carbon-based particle 100A allows for improvedelectrical conduction therein.

FIG. 17B shows the carbon-based particle of FIG. 7A withgraphene-on-graphene densification. For the example of FIG. 17B,surfaces 1700B shown in FIG. 17B and/or surfaces 1708A shown in FIG. 17Aat edge regions, at least partially planar surfaces of the branched,tree-like structure of section 1700A of carbon-based particle 100A, maybe densified upon the application, deposition, or otherwise growth ofmultiple additional graphene layers. Such densification processes,methods and/or procedures permit for the creation of intricate,multi-layer, and potentially nearly infinitely tunable 3D carbonstructures comprising combinations of 3D bundles of graphene sheets101B. Accordingly, such fine tunability accomplished bygraphene-on-graphene densification may facilitate the attainment ofparticular electrical conductivity values when carbon-based particle 100is integrated into an electrode of a battery.

FIG. 18A through FIG. 18C show real-life micrographs 1800A, 1800B, and1800C, respectively, of any one or more of the presently disclosedcarbon structures, include the carbon-based particle 100A and/or thecontiguous microstructures 107E shown in FIGS. 1A and 1E, respectively,at various increasing levels of magnification.

FIG. 18D shows a micrograph 1800D with a composite carbon agglomeratehaving an internal structure similar to that described for carbon-basedparticle 100A, complete with pores 105E and contiguous microstructures107E, and has been prepared both in size and composition forincorporation in a cathode for Li ion systems but can also be applicableto process and produce cages for Li on an anode. Randomly sized andshaped agglomerates can be used to fabricate any one or more of thepresently disclosed electrodes. Nevertheless, tuning procedures canallow for the production of carbon agglomerates and/or particles atregular expected sizes as well, potentially providing for both ease ofhandling and advantages in processing.

FIG. 18E shows a micrograph 1800E with an activated carbon structure forinfiltration with sulfur (S) used in a Li S system cathode as describedby at least any one or more of the presently disclosed carbon-basedstructures, including the contiguous microstructures 107E shown in FIG.1E. The activated carbon structure for infiltration with sulfur (S)shown in micrograph 1800E can be produced by a combined screw conveyorsystem or through other distinct steps. Thermal reactor producedmaterial has been shown to be more lithiophilic than un-doped and/orun-functionalized microwave-generated carbon structures. In someimplementations, the prevalence of organic and/or hydrocarbon-basedcontamination on the surface of few layer graphenes produced in thereactors may demand the performance of additional post processingrefinement steps.

FIG. 19A shows a schematic depiction 1900A of a 3D graphene-particlecathode scaffold, such as carbon scaffold 300B featuring sulfur (S)micro-confinement therein, suitable for scale-up and/or incorporationwith any one or more of the carbons presently disclosed, including usageas a formative material to produce contiguous microstructures 107E shownin FIG. 1E. In the example of FIG. 19A, graphene-based sheets and/orstructures containing sulfur entrainment and/or confinement 1902A invarious 3D cathode scaffolded structures or configurations, of variousthicknesses 1904A and 1906A, are shown. S inclusion in graphene-basedbattery chemistry provides desirable electric charge storage andretention measured in milliamp hours, further described by the synthesisof a graphene—sulfur composite material by wrapping poly(ethyleneglycol) (PEG) coated submicrometer sulfur particles with mildly oxidizedgraphene oxide sheets decorated by carbon black nanoparticles.

The PEG and graphene coating layers are important to accommodatingvolume expansion of the coated sulfur particles during discharge,trapping soluble polysulfide intermediates, and rendering the sulfurparticles electrically conducting. The resulting graphene—sulfurcomposite showed high and stable specific capacities up to ˜600 mAh/gover more than 100 cycles, representing a promising cathode material forrechargeable Li batteries with high energy density. Other studies haveshown that activated graphene (AG) with various specific surface areas,pore volumes, and average pore sizes have been fabricated and applied asa matrix for sulfur. The impacts of the AG pore structure parameters andsulfur loadings on the electrochemical performance of Li-sulfurbatteries are systematically investigated.

The results show that specific capacity, cycling performance, andCoulombic efficiency of the batteries are closely linked to the porestructure and sulfur loading. An AG3-sized (S) composite electrode witha high sulfur loading of 72 wt. % exhibited an excellent long-termcycling stability at 50% capacity retention over 1,000 cycles andextra-low-capacity fade rate (0.05% per cycle). In addition, when LiNO₃was used as an electrolyte additive, the AG3/S electrode exhibited asimilar capacity retention and high Coulombic efficiency at ˜98% over1,000 cycles. The excellent electrochemical performance of the series ofAG3/S electrodes is attributed to the mixed micro/mesoporous structure,high surface area, and good electrical conductivity of the AG matricesand the well-distributed sulfur within the micro/mesopores, which isbeneficial for electrical and ionic transfer during cycling.

FIG. 19B shows a 3D few-layer graphene anode scaffold, such as carbonscaffold 300 and/or lithiated carbon scaffold 400A prepared forincorporation within or usage as a formative material for a Li ion or LiS system anode with Li intercalation between graphene layers. In theexample of FIG. 19B, Li ions (Li+) are shown in various configurations1900B including as being intercalated into FLG 1902B and reversibleinclusion of Li metal in a carbon-based host scaffold 1904B. Liintercalation into bi-layer graphene may relate to and address the realcapacity of graphene and the Li-storage process in graphite, whichpresent problems in the field of Li ion batteries.

Corroborated by theoretical calculations, various physiochemicalcharacterizations of the staged lithium bilayer graphene productsfurther reveal the regular Li-intercalation phenomena and thereforefully illustrate this elementary lithium storage pattern oftwo-dimension. These findings not only make the commercial graphite thefirst electrode with clear lithium-storage process, but also guide thedevelopment of graphene materials in Li ion batteries. Li absorption andintercalation in single layer graphene and few layer graphene differs tothat associated with bulk graphite. For single layer graphene, thecluster expansion method is used to systemically search for the lowestenergy ionic configuration as a function of absorbed Li content. It ispredicted that there exists no Li arrangement that stabilizes Liabsorption on the surface of single layer graphene unless that surfaceincludes defects. From this result follows that defect poor single layergraphene exhibits significantly inferior capacity compared to bulkgraphite.

In some implementations, carbon-based particle films can include atleast the following particle-like properties, in addition to any one ormore of: sacrificial, as well as, supporting film substrates; tunablevelocity to substrate; tunable impact energy from implantation toadsorption; tunable thickness; and, tunable porosity; any one or more ofwhich can be integrated with additive type manufacturing capability.

In some implementations, any one or more of the presently disclosedcarbons and carbon-based structures can enable significant batteryperformance advantages over currently available Li-ion and/or Li Sbatteries, including: to achieving any one or more of the physicaland/or electrical energy storage and/or conductivity values including anenergy density in the range of approximately 400 to 650 (W·h)/kg, with amaximum theoretical value of 850 (W·h)/kg, and also including aspectswith a sulfur and/or sulfur-intercalated cathode of 650 (MAh)/g, and,aspects of the graphene sheets 102A and/or conductive carbon particlesinterspersed therewith to define pores and/or voids, etc., assubstantially discussed in connection with that shown in FIG. 1A throughFIG. 1E, with ionic Li (Li+) intercalated therein to ultimatelyachieving an energy density storage value of 900 to 2,000 (mAh)/g.

FIG. 20A shows cathode specific capacity levels over cycles and variousrepresentative sulfur-nano confinement as representative of applicationand/or usage of systems based on or using carbon-based particle 100A andderivatives thereof diagrams and images. Improved cathode specificcapacity, electrode level, as measured in mAh/g, is shown in graph 2008a for various compositions and/or compounds, any one or more of which atleast partially include carbon-based particle 100A formed with sintegrated therewith to enhance cathode specific capacity.

FIGS. 20B and 20C show charts regarding accelerated carbon tuning tomitigate polysulfide (PS) shuttle related issues, indicating thatincreasing the porosity of carbon-based materials, carbon-based particle100A and variations thereof, reduces PS shuttling, defined as wheresulfur S reach the negative electrode surface and undergo chemicalreduction, leading to unwanted automatic electrochemical cellself-discharge. Chart 2002B shown in FIG. 20B shows a mean intensitychange of low porosity carbon generally at higher levels than highporosity carbon. Chart 2002C shown in FIG. 20C shows high porositycarbon generally with higher levels of percentage capacity retentionover repeated battery usage cycles relative to low porosity carbon.

Tuning of carbon-based particle 100A may achieve more efficientfabrication including Li utilization and potential increase the rationof active material to inactive material within a battery electrode,binder reduction, improved uniformity and controlled electrochemicalreactions, such as battery electricity conductivity and/or activity.Parameters of carbon-based particle 100A can be tuned to achievespecific performance features as a function of the percentage of Liloading per unit area or volume of carbon-based particle 100A,including:

-   -   at low loading levels, less than capacity, compensating for        first charge losses/more effective SEI formation; at        saturation/matched loading, Li rich regions, galvanically        coupled to carbon,    -   oxidizing materials when in contact with electrolyte and        insertion of Li and/or Li-ions via intercalation between        graphene layers;    -   at excess loading levels, metallic Li is infiltrated into        engineered host carbon; configuring the host to serves to        accommodate/stabilize expansion of Li and suppress dendrite        formation as a result of increased Li surface area, enables        specific capacities commensurate with pure Li: >2,000 mAh/g;        and,    -   preparing Li ion processes/methodology directly transferable to        lithium-ion hybrid capacitors.

Ongoing challenges, related to the thermal and/or liquid infusion of Liand/or Li ion into carbon-based structures such as carbon-based particle100A as outlined in listing 2900E can include management of Lireactivity regarding surface tension, wettability at a solid-to-liquidelectrolyte interface; management of capillary Li and/or S infiltrationkinetics, engineering of electrical gradient through electrodethickness, gradation of Li infiltration such that it is highest atcurrent collector and transitions to a more ionic conductingconcentration and/or level at electrolyte interface, and, the carefullytuned engineering of surface chemistry by facilitating stable SEIformation in contact with electrolyte and minimize reactivity with air.

Disclosed aspects may build upon traditional two-dimensional (2D)plating, which may be similar to brightening agents in electroplating.In electroplating, the addition of chemical additives may often increasepolarization, decrease current density; such as, redirect currentdensity to low as opposed to high areas, such as protrusions; produce arelatively high nucleation rate, and result in a moderate chargetransfer rate. In the context of plating or stripping for battery chargeand discharge cycles, for batteries with electrodes equipped withcarbon-based particle 100A as shown in FIG. 1A through FIG. 1E, carbonfilm may serve as a flexible support for SEI formation as well as,redirecting current density to low, as opposed to high, areas.

Employed herein in a context of producing carbon-based particle 100A andintegrating it with a Li ion battery, cementation may be employed in anyone or more of the disclosed fabrication techniques. Cementation impliesa process of altering a metal by heating it in contact with a powderedsolid, precipitation in copper production may refer to and/or involve aheterogeneous process. Such a process may imply conditions wherereactants are components of two or more phases, such as solid and gas,solid and liquid, two immiscible liquids, or in which one or morereactants undergo chemical change at an interface, on the surface of asolid catalyst, in which ions are reduced to zero valence at a solidmetal surface, such as, Cu ions on Fe particle surface; and, where ironoxidizes and copper is reduced, such as copper being relatively higheron a galvanic series, similar to Li versus C.

Molten metals including Li metal can be managed for welding such thatany one or more of the mentioned techniques can be functionallyintegrated with and/or used to produce carbon-based particle 100A toenhance Li ion or Li S battery performance. Such ancillary processesand/or techniques include management of reactive metals via welding;classic metal inert gas (MIG), gas tungsten arc welding (GTAW) alsoreferred to as tungsten inert gas (TIG) and submerged arc welding (SAW)to utilize inert shielding gas to join reactive metals, such as Ti andAl, through a liquid metal process, such as by welding. Examples includeusing inert shielding gas to form liquid pools of reactive metal withoutoxidation, where delta Gf of oxides, such as TiO₂, Al2O₃, is on par withthat of Li₂O. Through controlled use of inert shielding gas aroundreactive metals, oxygen and moisture may effectively be managed in thepresence of reactive liquid metals. In such environments and conditions,liquid Li can be infiltrated into the carbon-based structures ofcarbon-based particle 100A through controlled shielding gasconfiguration and operation.

FIG. 21 shows Raman spectra for 3D N-doped FL graphene includingcharting for both pristine carbon and N-dope carbon. In the example ofFIG. 21 , Raman spectra for 3D N-doped FL graphene 2100 includes 2D peak2102 at approximately 2730 cm-1 and D peaks 2104, 2106 at approximately1600 cm⁻¹ and 1400 cm⁻¹, respectively.

FIG. 22 shows various properties associated with bilayer graphene 2200.In the example of FIG. 22 , a sample bilayer graphene infrastructure2200 is shown with two layers of graphene oriented in the positionshown, understood as devices which contained just one, two, or threeatomic layers. Schematic 2202 shows approximate spacing measurements of1.42 Å, 1.94 Å and/or 3.35 Å between individual graphene sheets.Schematic 2204 shows various example defective sites 2206 and/or 2208what may occur within a defined vicinity of an edge plane and/or assistwith the creation of carbon-based particle structures including one ormore graphene sheets. Schematic 2210 shows various model diagrams 2212of a top view of a hard-sphere carbon-particle model.

In some implementations, reactor tuning can be performed to, forexample, any one or more of: increase FL graphene spacing, reduce Vander Waal forces; control doping; promote carbon vacancy formation; anddecreases Li adsorption energy and/or increase Li capacity. Li ionintercalation may, for example, shift graphene sheet stacks from an A-Bconfiguration to A with intercalation accommodated by increased spacing,where, for example, in graphite, A-A may shift back to A-B withde-intercalation; and, in FL graphene, in FL graphene, AA stackingremains with de-intercalation, such as by maintaining increased spacing.Such stacking configurations may be associated with the carbon-basedparticle 100A shown in FIG. 1A through FIG. 1E.

FIG. 23 shows an illustrative flowchart for depicting an exampleoperation 2300 for preparing a 3D scaffolded film containingcarbon-based particles. In the example of FIG. 23 , method 3300 includespreparing a 3D scaffolded film containing carbon-based particles thereinat operation 2304 by providing the 3D scaffolded film to a roll-to-rollprocessing device or apparatus at operation 2306. Carbon rich electrodesmay be deposited on the 3D scaffolded film at operation 2308; and,processing the 3D scaffolded film on the roll-to-roll processing deviceor apparatus independent of application of chemically inactive bindingmaterials may occur at operation 2310 prior to conclusion of the method2300 at operation 2312.

In the foregoing specification, the disclosure has been described withreference to specific examples. It will however be evident that variousmodifications and changes may be made thereto without departing from thebroader spirit and scope of the disclosure. For example, theabove-described process flows are described with reference to aparticular ordering of process actions. However, the ordering of many ofthe described process actions may be changed without affecting the scopeor operation of the disclosure. The specification and drawings are to beregarded in an illustrative sense rather than in a restrictive sense.

What is claimed is:
 1. A battery comprising: a cathode and an anodeseparated by a separator layer; an electrically insulating carbon layerat least partially encapsulating the anode; a plurality of carbonnano-onions (CNOs) defining one or more interstitial pores interspersedthroughout the electrically insulating carbon layer; and an electrolytein contact with the electrically insulating carbon layer and thecathode.
 2. The battery of claim 1, wherein the electrically insulatingcarbon layer comprises graphene oxide.
 3. The battery of claim 1,wherein the one or more interstitial pores are configured to transportlithium ions between the anode and the cathode in a bulk phase of theelectrolyte.
 4. The battery of claim 1, wherein the cathode furthercomprises a porous carbon-based structure configured to expand andcontract a volume of the cathode during operational cycling of thebattery.
 5. The battery of claim 1, further comprising a film, having aYoung's modulus greater than approximately 6 GPa, disposed on theelectrically insulating carbon layer.
 6. The battery of claim 1, whereinthe electrically insulating carbon layer is configured to inhibit growthof Lithium dendritic structures from the anode.
 7. The battery of claim1, wherein the separator layer is configured to transport lithium ionsbetween the anode and the cathode.
 8. The battery of claim 1, wherein atleast some of the plurality of CNOs have a surface area of approximately10 m²/g to 90 m²/g.
 9. The battery of claim 1, wherein the plurality ofCNOs is configured to adsorb polysulfide produced at or near thecathode.
 10. The battery of claim 9, wherein the plurality of CNOs isfurther configured to inhibit polysulfide anions from contacting theanode.
 11. The battery of claim 1, wherein the anode comprises a metalfoil.
 12. The battery of claim 1, wherein the anode comprises acarbon-based composite structure including one or more of a plurality ofcarbon nano-onions or a plurality of graphene platelets fused together.13. The battery of claim 12, wherein the carbon-based compositestructure is configured to be infiltrated by a molten lithium metal. 14.The battery of claim 13, wherein the molten Lithium metal includes oneor more Lithium-containing droplets, Lithium-containing domains, singlecrystalline domains, or poly-crystalline domains.
 15. The battery ofclaim 1, wherein the electrically insulating carbon layer comprisesinterlayer pi-pi bonds.
 16. The battery of claim 1, wherein theelectrically insulating carbon layer includes a stack comprising two ormore electrically insulating carbon films, wherein each electricallyinsulating carbon film is substantially flat.
 17. The battery of claim16, wherein the stack is configured to inhibit crack growth in theanode.
 18. The battery of claim 16, wherein the stack further comprisesa plurality of gap regions.
 19. The battery of claim 18, wherein thestack further comprises a binder.
 20. The battery of claim 1, whereinthe electrically insulating carbon layer is configured to producelithium hydroxide (LiOH) based on a chemical reaction with Lithium metalprovided by the anode.